25131781 has 2 divisors, whose sum is σ = 25131782. Its totient is φ = 25131780.

The previous prime is 25131761. The next prime is 25131791. The reversal of 25131781 is 18713152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13942756 + 11189025 = 3734^2 + 3345^2 .

It is a cyclic number.

It is not a de Polignac number, because 25131781 - 2⁵ = 25131749 is a prime.

It is a super-2 number, since 2×25131781² = 1263212832463922, which contains 22 as substring.

It is equal to p_1573723 and since 25131781 and 1573723 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25131751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12565890 + 12565891.

It is an arithmetic number, because the mean of its divisors is an integer number (12565891).

Almost surely, 2^25131781 is an apocalyptic number.

It is an amenable number.

25131781 is a deficient number, since it is larger than the sum of its proper divisors (1).

25131781 is an equidigital number, since it uses as much as digits as its factorization.

25131781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1680, while the sum is 28.

The square root of 25131781 is about 5013.1607793886. The cubic root of 25131781 is about 292.9146470236.

The spelling of 25131781 in words is "twenty-five million, one hundred thirty-one thousand, seven hundred eighty-one".