21722437 has 4 divisors (see below), whose sum is σ = 23697216. Its totient is φ = 19747660.

The previous prime is 21722429. The next prime is 21722483. The reversal of 21722437 is 73422712.

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 21722437 - 2³ = 21722429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21722837) 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, 987373 + ... + 987394.

It is an arithmetic number, because the mean of its divisors is an integer number (5924304).

Almost surely, 2^21722437 is an apocalyptic number.

It is an amenable number.

21722437 is a deficient number, since it is larger than the sum of its proper divisors (1974779).

21722437 is a wasteful number, since it uses less digits than its factorization.

21722437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1974778.

The product of its digits is 4704, while the sum is 28.

The square root of 21722437 is about 4660.7335259592. The cubic root of 21722437 is about 279.0205446432.

The spelling of 21722437 in words is "twenty-one million, seven hundred twenty-two thousand, four hundred thirty-seven".