261969840 has 360 divisors, whose sum is σ = 1008518784. Its totient is φ = 60825600.

The previous prime is 261969823. The next prime is 261969857. The reversal of 261969840 is 48969162.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (261969823) and next prime (261969857).

It is a tau number, because it is divible by the number of its divisors (360).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2700672 + ... + 2700768.

Almost surely, 2^261969840 is an apocalyptic number.

261969840 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 261969840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (504259392).

261969840 is an abundant number, since it is smaller than the sum of its proper divisors (746548944).

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

261969840 is a wasteful number, since it uses less digits than its factorization.

261969840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169 (or 149 counting only the distinct ones).

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

The square root of 261969840 is about 16185.4823839143. The cubic root of 261969840 is about 639.8582368302.

The spelling of 261969840 in words is "two hundred sixty-one million, nine hundred sixty-nine thousand, eight hundred forty".