25151981 has 4 divisors (see below), whose sum is σ = 25164000. Its totient is φ = 25139964.

The previous prime is 25151933. The next prime is 25152013. The reversal of 25151981 is 18915152.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 25151981 - 2¹⁴ = 25135597 is a prime.

It is a super-2 number, since 2×25151981² = 1265244296448722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25151281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1961 + ... + 7358.

It is an arithmetic number, because the mean of its divisors is an integer number (6291000).

Almost surely, 2^25151981 is an apocalyptic number.

It is an amenable number.

25151981 is a deficient number, since it is larger than the sum of its proper divisors (12019).

25151981 is an equidigital number, since it uses as much as digits as its factorization.

25151981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12018.

The product of its digits is 3600, while the sum is 32.

The square root of 25151981 is about 5015.1750717198. The cubic root of 25151981 is about 292.9931040090.

The spelling of 25151981 in words is "twenty-five million, one hundred fifty-one thousand, nine hundred eighty-one".