21104537 has 4 divisors (see below), whose sum is σ = 21401856. Its totient is φ = 20807220.

The previous prime is 21104527. The next prime is 21104543. The reversal of 21104537 is 73540112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21104537 - 2¹⁰ = 21103513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21104507) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 148553 + ... + 148694.

It is an arithmetic number, because the mean of its divisors is an integer number (5350464).

Almost surely, 2^21104537 is an apocalyptic number.

It is an amenable number.

21104537 is a deficient number, since it is larger than the sum of its proper divisors (297319).

21104537 is an equidigital number, since it uses as much as digits as its factorization.

21104537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 297318.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21104537 is about 4593.9674574381. The cubic root of 21104537 is about 276.3494532136.

Adding to 21104537 its reverse (73540112), we get a palindrome (94644649).

The spelling of 21104537 in words is "twenty-one million, one hundred four thousand, five hundred thirty-seven".