25640163261 has 24 divisors (see below), whose sum is σ = 38842277760. Its totient is φ = 16267226976.

The previous prime is 25640163251. The next prime is 25640163277. The reversal of 25640163261 is 16236104652.

25640163261 is a `hidden beast` number, since 2 + 5 + 640 + 1 + 6 + 3 + 2 + 6 + 1 = 666.

It is not a de Polignac number, because 25640163261 - 2¹³ = 25640155069 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25640163221) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 273601 + ... + 355158.

It is an arithmetic number, because the mean of its divisors is an integer number (1618428240).

Almost surely, 2^25640163261 is an apocalyptic number.

It is an amenable number.

25640163261 is a deficient number, since it is larger than the sum of its proper divisors (13202114499).

25640163261 is a wasteful number, since it uses less digits than its factorization.

25640163261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 628985 (or 628982 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The spelling of 25640163261 in words is "twenty-five billion, six hundred forty million, one hundred sixty-three thousand, two hundred sixty-one".