25187821 has 2 divisors, whose sum is σ = 25187822. Its totient is φ = 25187820.

The previous prime is 25187803. The next prime is 25187831. The reversal of 25187821 is 12878152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15515721 + 9672100 = 3939^2 + 3110^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25187821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25187831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12593910 + 12593911.

It is an arithmetic number, because the mean of its divisors is an integer number (12593911).

Almost surely, 2^25187821 is an apocalyptic number.

It is an amenable number.

25187821 is a deficient number, since it is larger than the sum of its proper divisors (1).

25187821 is an equidigital number, since it uses as much as digits as its factorization.

25187821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8960, while the sum is 34.

The square root of 25187821 is about 5018.7469551672. The cubic root of 25187821 is about 293.1322035773.

The spelling of 25187821 in words is "twenty-five million, one hundred eighty-seven thousand, eight hundred twenty-one".