21258401 has 2 divisors, whose sum is σ = 21258402. Its totient is φ = 21258400.

The previous prime is 21258373. The next prime is 21258407. The reversal of 21258401 is 10485212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17648401 + 3610000 = 4201^2 + 1900^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21258401 is a prime.

It is a super-2 number, since 2×21258401² = 903839226153602, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21258407) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10629200 + 10629201.

It is an arithmetic number, because the mean of its divisors is an integer number (10629201).

Almost surely, 2^21258401 is an apocalyptic number.

It is an amenable number.

21258401 is a deficient number, since it is larger than the sum of its proper divisors (1).

21258401 is an equidigital number, since it uses as much as digits as its factorization.

21258401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21258401 is about 4610.6833549920. The cubic root of 21258401 is about 277.0194089455.

The spelling of 21258401 in words is "twenty-one million, two hundred fifty-eight thousand, four hundred one".