21320637 has 8 divisors (see below), whose sum is σ = 30614304. Its totient is φ = 13120368.

The previous prime is 21320581. The next prime is 21320639. The reversal of 21320637 is 73602312.

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

It is not a de Polignac number, because 21320637 - 2¹⁴ = 21304253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320639) 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, 273303 + ... + 273380.

It is an arithmetic number, because the mean of its divisors is an integer number (3826788).

Almost surely, 2^21320637 is an apocalyptic number.

It is an amenable number.

21320637 is a deficient number, since it is larger than the sum of its proper divisors (9293667).

21320637 is a wasteful number, since it uses less digits than its factorization.

21320637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 546699.

The product of its (nonzero) digits is 1512, while the sum is 24.

The square root of 21320637 is about 4617.4275305629. The cubic root of 21320637 is about 277.2894791602.

Adding to 21320637 its reverse (73602312), we get a palindrome (94922949).

The spelling of 21320637 in words is "twenty-one million, three hundred twenty thousand, six hundred thirty-seven".