21056401 has 2 divisors, whose sum is σ = 21056402. Its totient is φ = 21056400.

The previous prime is 21056381. The next prime is 21056437. The reversal of 21056401 is 10465012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18284176 + 2772225 = 4276^2 + 1665^2 .

It is a cyclic number.

It is not a de Polignac number, because 21056401 - 2¹¹ = 21054353 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21056491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10528200 + 10528201.

It is an arithmetic number, because the mean of its divisors is an integer number (10528201).

Almost surely, 2^21056401 is an apocalyptic number.

It is an amenable number.

21056401 is a deficient number, since it is larger than the sum of its proper divisors (1).

21056401 is an equidigital number, since it uses as much as digits as its factorization.

21056401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21056401 is about 4588.7254221625. The cubic root of 21056401 is about 276.1391906270.

The spelling of 21056401 in words is "twenty-one million, fifty-six thousand, four hundred one".