21255401 has 2 divisors, whose sum is σ = 21255402. Its totient is φ = 21255400.

The previous prime is 21255383. The next prime is 21255407. The reversal of 21255401 is 10455212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21114025 + 141376 = 4595^2 + 376^2 .

It is a cyclic number.

It is not a de Polignac number, because 21255401 - 2¹⁰ = 21254377 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21255407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627700 + 10627701.

It is an arithmetic number, because the mean of its divisors is an integer number (10627701).

Almost surely, 2^21255401 is an apocalyptic number.

It is an amenable number.

21255401 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255401 is an equidigital number, since it uses as much as digits as its factorization.

21255401 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 21255401 is about 4610.3580121288. The cubic root of 21255401 is about 277.0063772768.

The spelling of 21255401 in words is "twenty-one million, two hundred fifty-five thousand, four hundred one".