261665573346556 has 48 divisors (see below), whose sum is σ = 464370388886880. Its totient is φ = 129000120480000.

The previous prime is 261665573346547. The next prime is 261665573346577. The reversal of 261665573346556 is 655643375566162.

It is a happy number.

It is a super-2 number, since 2×261665573346556² (a number of 30 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (70) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 99916986 + ... + 102502366.

It is an arithmetic number, because the mean of its divisors is an integer number (9674383101810).

Almost surely, 2^{261665573346556} is an apocalyptic number.

It is an amenable number.

261665573346556 is a deficient number, since it is larger than the sum of its proper divisors (202704815540324).

261665573346556 is a wasteful number, since it uses less digits than its factorization.

261665573346556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2586526 (or 2586524 counting only the distinct ones).

The product of its digits is 2449440000, while the sum is 70.

The spelling of 261665573346556 in words is "two hundred sixty-one trillion, six hundred sixty-five billion, five hundred seventy-three million, three hundred forty-six thousand, five hundred fifty-six".