21893537 has 2 divisors, whose sum is σ = 21893538. Its totient is φ = 21893536.

The previous prime is 21893527. The next prime is 21893551. The reversal of 21893537 is 73539812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21864976 + 28561 = 4676^2 + 169^2 .

It is a cyclic number.

It is not a de Polignac number, because 21893537 - 2⁸ = 21893281 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 21893537.

It is not a weakly prime, because it can be changed into another prime (21893527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10946768 + 10946769.

It is an arithmetic number, because the mean of its divisors is an integer number (10946769).

Almost surely, 2^21893537 is an apocalyptic number.

It is an amenable number.

21893537 is a deficient number, since it is larger than the sum of its proper divisors (1).

21893537 is an equidigital number, since it uses as much as digits as its factorization.

21893537 is an evil number, because the sum of its binary digits is even.

The product of its digits is 45360, while the sum is 38.

The square root of 21893537 is about 4679.0530024782. The cubic root of 21893537 is about 279.7512118331.

The spelling of 21893537 in words is "twenty-one million, eight hundred ninety-three thousand, five hundred thirty-seven".