21221953 has 2 divisors, whose sum is σ = 21221954. Its totient is φ = 21221952.

The previous prime is 21221947. The next prime is 21222013. The reversal of 21221953 is 35912212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11778624 + 9443329 = 3432^2 + 3073^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221953 - 2⁹ = 21221441 is a prime.

It is not a weakly prime, because it can be changed into another prime (21221923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610976 + 10610977.

It is an arithmetic number, because the mean of its divisors is an integer number (10610977).

Almost surely, 2^21221953 is an apocalyptic number.

It is an amenable number.

21221953 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221953 is an equidigital number, since it uses as much as digits as its factorization.

21221953 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1080, while the sum is 25.

The square root of 21221953 is about 4606.7290999146. The cubic root of 21221953 is about 276.8609997388.

The spelling of 21221953 in words is "twenty-one million, two hundred twenty-one thousand, nine hundred fifty-three".