261500820 has 48 divisors (see below), whose sum is σ = 836803968. Its totient is φ = 59771520.

The previous prime is 261500807. The next prime is 261500821. The reversal of 261500820 is 28005162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261500821) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 310891 + ... + 311730.

It is an arithmetic number, because the mean of its divisors is an integer number (17433416).

Almost surely, 2^261500820 is an apocalyptic number.

261500820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261500820 is an abundant number, since it is smaller than the sum of its proper divisors (575303148).

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

261500820 is a wasteful number, since it uses less digits than its factorization.

261500820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622640 (or 622638 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 261500820 is about 16170.9869828653. The cubic root of 261500820 is about 639.4761501138.

Adding to 261500820 its reverse (28005162), we get a palindrome (289505982).

The spelling of 261500820 in words is "two hundred sixty-one million, five hundred thousand, eight hundred twenty".