21372889 has 2 divisors, whose sum is σ = 21372890. Its totient is φ = 21372888.

The previous prime is 21372887. The next prime is 21372937. The reversal of 21372889 is 98827312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12131289 + 9241600 = 3483^2 + 3040^2 .

It is a cyclic number.

It is not a de Polignac number, because 21372889 - 2¹ = 21372887 is a prime.

Together with 21372887, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21372887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10686444 + 10686445.

It is an arithmetic number, because the mean of its divisors is an integer number (10686445).

Almost surely, 2^21372889 is an apocalyptic number.

It is an amenable number.

21372889 is a deficient number, since it is larger than the sum of its proper divisors (1).

21372889 is an equidigital number, since it uses as much as digits as its factorization.

21372889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 40.

The square root of 21372889 is about 4623.0821969764. The cubic root of 21372889 is about 277.5158187016.

The spelling of 21372889 in words is "twenty-one million, three hundred seventy-two thousand, eight hundred eighty-nine".