25666161521 has 32 divisors (see below), whose sum is σ = 35194134528. Its totient is φ = 18068351040.

The previous prime is 25666161509. The next prime is 25666161523. The reversal of 25666161521 is 12516166652.

It is a cyclic number.

It is not a de Polignac number, because 25666161521 - 2¹⁰ = 25666160497 is a prime.

It is a super-2 number, since 2×25666161521² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (25666161523) 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, 225725 + ... + 319818.

It is an arithmetic number, because the mean of its divisors is an integer number (1099816704).

Almost surely, 2^25666161521 is an apocalyptic number.

It is an amenable number.

25666161521 is a deficient number, since it is larger than the sum of its proper divisors (9527973007).

25666161521 is a wasteful number, since it uses less digits than its factorization.

25666161521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 545621.

The product of its digits is 129600, while the sum is 41.

The spelling of 25666161521 in words is "twenty-five billion, six hundred sixty-six million, one hundred sixty-one thousand, five hundred twenty-one".