261402564 has 12 divisors (see below), whose sum is σ = 609939344. Its totient is φ = 87134184.

The previous prime is 261402529. The next prime is 261402569. The reversal of 261402564 is 465204162.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (261402569) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10891762 + ... + 10891785.

Almost surely, 2^261402564 is an apocalyptic number.

It is an amenable number.

261402564 is an abundant number, since it is smaller than the sum of its proper divisors (348536780).

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

261402564 is a wasteful number, since it uses less digits than its factorization.

261402564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21783554 (or 21783552 counting only the distinct ones).

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

The square root of 261402564 is about 16167.9486639462. The cubic root of 261402564 is about 639.3960480836.

The spelling of 261402564 in words is "two hundred sixty-one million, four hundred two thousand, five hundred sixty-four".