25406661987 has 16 divisors (see below), whose sum is σ = 43016570880. Its totient is φ = 14518092456.

The previous prime is 25406661977. The next prime is 25406662007. The reversal of 25406661987 is 78916660452.

It is not a de Polignac number, because 25406661987 - 2⁶ = 25406661923 is a prime.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (25406661977) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 67213203 + ... + 67213580.

It is an arithmetic number, because the mean of its divisors is an integer number (2688535680).

Almost surely, 2^25406661987 is an apocalyptic number.

25406661987 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

25406661987 is a deficient number, since it is larger than the sum of its proper divisors (17609908893).

25406661987 is a wasteful number, since it uses less digits than its factorization.

25406661987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134426799 (or 134426793 counting only the distinct ones).

The product of its (nonzero) digits is 4354560, while the sum is 54.

The spelling of 25406661987 in words is "twenty-five billion, four hundred six million, six hundred sixty-one thousand, nine hundred eighty-seven".