25540721 has 2 divisors, whose sum is σ = 25540722. Its totient is φ = 25540720.

The previous prime is 25540717. The next prime is 25540727. The reversal of 25540721 is 12704552.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23902321 + 1638400 = 4889^2 + 1280^2 .

It is a cyclic number.

It is not a de Polignac number, because 25540721 - 2² = 25540717 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (25540727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12770360 + 12770361.

It is an arithmetic number, because the mean of its divisors is an integer number (12770361).

Almost surely, 2^25540721 is an apocalyptic number.

It is an amenable number.

25540721 is a deficient number, since it is larger than the sum of its proper divisors (1).

25540721 is an equidigital number, since it uses as much as digits as its factorization.

25540721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2800, while the sum is 26.

The square root of 25540721 is about 5053.7828406056. The cubic root of 25540721 is about 294.4948589704.

The spelling of 25540721 in words is "twenty-five million, five hundred forty thousand, seven hundred twenty-one".