261664704 has 252 divisors, whose sum is σ = 891381504. Its totient is φ = 73156608.

The previous prime is 261664699. The next prime is 261664723. The reversal of 261664704 is 407466162.

261664704 is a `hidden beast` number, since 2 + 6 + 1 + 6 + 647 + 0 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (252).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2060289 + ... + 2060415.

Almost surely, 2^261664704 is an apocalyptic number.

261664704 is a gapful number since it is divisible by the number (24) 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 261664704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (445690752).

261664704 is an abundant number, since it is smaller than the sum of its proper divisors (629716800).

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

261664704 is a wasteful number, since it uses less digits than its factorization.

261664704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232 (or 212 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 36.

The square root of 261664704 is about 16176.0534123747. The cubic root of 261664704 is about 639.6097099552.

The spelling of 261664704 in words is "two hundred sixty-one million, six hundred sixty-four thousand, seven hundred four".