21589481 has 2 divisors, whose sum is σ = 21589482. Its totient is φ = 21589480.

The previous prime is 21589471. The next prime is 21589487. The reversal of 21589481 is 18498512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21576025 + 13456 = 4645^2 + 116^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21589481 is a prime.

It is a super-2 number, since 2×21589481² = 932211379698722, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21589487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10794740 + 10794741.

It is an arithmetic number, because the mean of its divisors is an integer number (10794741).

Almost surely, 2^21589481 is an apocalyptic number.

It is an amenable number.

21589481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21589481 is an equidigital number, since it uses as much as digits as its factorization.

21589481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23040, while the sum is 38.

The square root of 21589481 is about 4646.4482134207. The cubic root of 21589481 is about 278.4501144604.

The spelling of 21589481 in words is "twenty-one million, five hundred eighty-nine thousand, four hundred eighty-one".