25640418388 has 36 divisors (see below), whose sum is σ = 48613309500. Its totient is φ = 11827835136.

The previous prime is 25640418383. The next prime is 25640418389. The reversal of 25640418388 is 88381404652.

It can be written as a sum of positive squares in 6 ways, for example, as 16876088464 + 8764329924 = 129908^2 + 93618^2 .

It is a super-2 number, since 2×25640418388² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25640418383) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1435738 + ... + 1453486.

Almost surely, 2^25640418388 is an apocalyptic number.

It is an amenable number.

25640418388 is a deficient number, since it is larger than the sum of its proper divisors (22972891112).

25640418388 is a wasteful number, since it uses less digits than its factorization.

25640418388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19916 (or 19901 counting only the distinct ones).

The product of its (nonzero) digits is 1474560, while the sum is 49.

The spelling of 25640418388 in words is "twenty-five billion, six hundred forty million, four hundred eighteen thousand, three hundred eighty-eight".