21573137 has 8 divisors (see below), whose sum is σ = 21969792. Its totient is φ = 21179200.

The previous prime is 21573131. The next prime is 21573163. The reversal of 21573137 is 73137512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21573137 - 2⁴ = 21573121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21573131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21593 + ... + 22569.

It is an arithmetic number, because the mean of its divisors is an integer number (2746224).

Almost surely, 2^21573137 is an apocalyptic number.

It is an amenable number.

21573137 is a deficient number, since it is larger than the sum of its proper divisors (396655).

21573137 is an equidigital number, since it uses as much as digits as its factorization.

21573137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1359.

The product of its digits is 4410, while the sum is 29.

The square root of 21573137 is about 4644.6891176913. The cubic root of 21573137 is about 278.3798311965.

The spelling of 21573137 in words is "twenty-one million, five hundred seventy-three thousand, one hundred thirty-seven".