25400021 has 2 divisors, whose sum is σ = 25400022. Its totient is φ = 25400020.

The previous prime is 25400009. The next prime is 25400047. The reversal of 25400021 is 12000452.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15319396 + 10080625 = 3914^2 + 3175^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25400021 is a prime.

It is a super-2 number, since 2×25400021² = 1290322133600882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 25399969 and 25400005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25400051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12700010 + 12700011.

It is an arithmetic number, because the mean of its divisors is an integer number (12700011).

Almost surely, 2^25400021 is an apocalyptic number.

It is an amenable number.

25400021 is a deficient number, since it is larger than the sum of its proper divisors (1).

25400021 is an equidigital number, since it uses as much as digits as its factorization.

25400021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 80, while the sum is 14.

The square root of 25400021 is about 5039.8433507402. The cubic root of 25400021 is about 293.9530869042.

Adding to 25400021 its reverse (12000452), we get a palindrome (37400473).

The spelling of 25400021 in words is "twenty-five million, four hundred thousand, twenty-one".