261399057983 has 32 divisors (see below), whose sum is σ = 319739904000. Its totient is φ = 208719231840.

The previous prime is 261399057971. The next prime is 261399057991. The reversal of 261399057983 is 389750993162.

It is a happy number.

It is a Cunningham number, because it is equal to 511272²-1.

It is not a de Polignac number, because 261399057983 - 2⁸ = 261399057727 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261399057923) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3542378 + ... + 3615416.

It is an arithmetic number, because the mean of its divisors is an integer number (9991872000).

Almost surely, 2^261399057983 is an apocalyptic number.

261399057983 is a deficient number, since it is larger than the sum of its proper divisors (58340846017).

261399057983 is a wasteful number, since it uses less digits than its factorization.

261399057983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73515.

The product of its (nonzero) digits is 22044960, while the sum is 62.

The spelling of 261399057983 in words is "two hundred sixty-one billion, three hundred ninety-nine million, fifty-seven thousand, nine hundred eighty-three".