21292021 has 2 divisors, whose sum is σ = 21292022. Its totient is φ = 21292020.

The previous prime is 21292013. The next prime is 21292031. The reversal of 21292021 is 12029212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21288996 + 3025 = 4614^2 + 55^2 .

It is a cyclic number.

It is not a de Polignac number, because 21292021 - 2³ = 21292013 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21292021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21292031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10646010 + 10646011.

It is an arithmetic number, because the mean of its divisors is an integer number (10646011).

Almost surely, 2^21292021 is an apocalyptic number.

It is an amenable number.

21292021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21292021 is an equidigital number, since it uses as much as digits as its factorization.

21292021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 21292021 is about 4614.3277950315. The cubic root of 21292021 is about 277.1653667272.

The spelling of 21292021 in words is "twenty-one million, two hundred ninety-two thousand, twenty-one".