21080737 has 4 divisors (see below), whose sum is σ = 21164976. Its totient is φ = 20996500.

The previous prime is 21080711. The next prime is 21080743. The reversal of 21080737 is 73708012.

It is a happy number.

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 21080737 - 2¹⁵ = 21047969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21080777) 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, 41743 + ... + 42244.

It is an arithmetic number, because the mean of its divisors is an integer number (5291244).

Almost surely, 2^21080737 is an apocalyptic number.

It is an amenable number.

21080737 is a deficient number, since it is larger than the sum of its proper divisors (84239).

21080737 is an equidigital number, since it uses as much as digits as its factorization.

21080737 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84238.

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 21080737 is about 4591.3763731587. The cubic root of 21080737 is about 276.2455325745.

Adding to 21080737 its reverse (73708012), we get a palindrome (94788749).

The spelling of 21080737 in words is "twenty-one million, eighty thousand, seven hundred thirty-seven".