21990937 has 4 divisors (see below), whose sum is σ = 22003920. Its totient is φ = 21977956.

The previous prime is 21990907. The next prime is 21990949. The reversal of 21990937 is 73909912.

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 a de Polignac number, because none of the positive numbers 2^k-21990937 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21990937.

It is not an unprimeable number, because it can be changed into a prime (21990907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3487 + ... + 7492.

It is an arithmetic number, because the mean of its divisors is an integer number (5500980).

Almost surely, 2^21990937 is an apocalyptic number.

It is an amenable number.

21990937 is a deficient number, since it is larger than the sum of its proper divisors (12983).

21990937 is a wasteful number, since it uses less digits than its factorization.

21990937 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12982.

The product of its (nonzero) digits is 30618, while the sum is 40.

The square root of 21990937 is about 4689.4495412575. The cubic root of 21990937 is about 280.1654506861.

The spelling of 21990937 in words is "twenty-one million, nine hundred ninety thousand, nine hundred thirty-seven".