261499680 has 288 divisors, whose sum is σ = 981030960. Its totient is φ = 63037440.

The previous prime is 261499657. The next prime is 261499703. The reversal of 261499680 is 86994162.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (261499657) and next prime (261499703).

It can be written as a sum of positive squares in 8 ways, for example, as 55175184 + 206324496 = 7428^2 + 14364^2 .

It is a tau number, because it is divible by the number of its divisors (288).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1141806 + ... + 1142034.

Almost surely, 2^261499680 is an apocalyptic number.

261499680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261499680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (490515480).

261499680 is an abundant number, since it is smaller than the sum of its proper divisors (719531280).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261499680 is a wasteful number, since it uses less digits than its factorization.

261499680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324 (or 313 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The square root of 261499680 is about 16170.9517345146. The cubic root of 261499680 is about 639.4752208575.

The spelling of 261499680 in words is "two hundred sixty-one million, four hundred ninety-nine thousand, six hundred eighty".