25643961 has 12 divisors (see below), whose sum is σ = 42332992. Its totient is φ = 14653656.

The previous prime is 25643957. The next prime is 25644029. The reversal of 25643961 is 16934652.

It is a happy number.

25643961 is a `hidden beast` number, since 2 + 5 + 643 + 9 + 6 + 1 = 666.

It is not a de Polignac number, because 25643961 - 2² = 25643957 is a prime.

It is a super-2 number, since 2×25643961² = 1315225471539042, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25643911) 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, 203461 + ... + 203586.

Almost surely, 2^25643961 is an apocalyptic number.

25643961 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

25643961 is a deficient number, since it is larger than the sum of its proper divisors (16689031).

25643961 is a wasteful number, since it uses less digits than its factorization.

25643961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407060 (or 407057 counting only the distinct ones).

The product of its digits is 38880, while the sum is 36.

The square root of 25643961 is about 5063.9866705986. The cubic root of 25643961 is about 294.8911251968.

The spelling of 25643961 in words is "twenty-five million, six hundred forty-three thousand, nine hundred sixty-one".