261320642564 has 24 divisors (see below), whose sum is σ = 477493291968. Its totient is φ = 124901108640.

The previous prime is 261320642563. The next prime is 261320642581. The reversal of 261320642564 is 465246023162.

It is not an unprimeable number, because it can be changed into a prime (261320642563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 742382 + ... + 1036229.

It is an arithmetic number, because the mean of its divisors is an integer number (19895553832).

Almost surely, 2^261320642564 is an apocalyptic number.

It is an amenable number.

261320642564 is a deficient number, since it is larger than the sum of its proper divisors (216172649404).

261320642564 is a wasteful number, since it uses less digits than its factorization.

261320642564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1780235 (or 1780233 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 41.

The spelling of 261320642564 in words is "two hundred sixty-one billion, three hundred twenty million, six hundred forty-two thousand, five hundred sixty-four".