261520644 has 72 divisors (see below), whose sum is σ = 774391968. Its totient is φ = 67925760.

The previous prime is 261520621. The next prime is 261520657. The reversal of 261520644 is 446025162.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13749 + ... + 26684.

It is an arithmetic number, because the mean of its divisors is an integer number (10755444).

Almost surely, 2^261520644 is an apocalyptic number.

It is an amenable number.

261520644 is an abundant number, since it is smaller than the sum of its proper divisors (512871324).

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

261520644 is a wasteful number, since it uses less digits than its factorization.

261520644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40465 (or 40456 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 30.

The square root of 261520644 is about 16171.5999208489. The cubic root of 261520644 is about 639.4923089604.

The spelling of 261520644 in words is "two hundred sixty-one million, five hundred twenty thousand, six hundred forty-four".