21537361 has 4 divisors (see below), whose sum is σ = 22473792. Its totient is φ = 20600932.

The previous prime is 21537349. The next prime is 21537379. The reversal of 21537361 is 16373512.

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 21537361 - 2¹³ = 21529169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21537311) 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, 468181 + ... + 468226.

It is an arithmetic number, because the mean of its divisors is an integer number (5618448).

Almost surely, 2^21537361 is an apocalyptic number.

It is an amenable number.

21537361 is a deficient number, since it is larger than the sum of its proper divisors (936431).

21537361 is an equidigital number, since it uses as much as digits as its factorization.

21537361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 936430.

The product of its digits is 3780, while the sum is 28.

The square root of 21537361 is about 4640.8362393000. The cubic root of 21537361 is about 278.2258615120.

The spelling of 21537361 in words is "twenty-one million, five hundred thirty-seven thousand, three hundred sixty-one".