21969437 has 4 divisors (see below), whose sum is σ = 25107936. Its totient is φ = 18830940.

The previous prime is 21969407. The next prime is 21969449. The reversal of 21969437 is 73496912.

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 21969437 - 2¹⁰ = 21968413 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21969394 and 21969403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21969407) 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, 1569239 + ... + 1569252.

It is an arithmetic number, because the mean of its divisors is an integer number (6276984).

Almost surely, 2^21969437 is an apocalyptic number.

It is an amenable number.

21969437 is a deficient number, since it is larger than the sum of its proper divisors (3138499).

21969437 is an equidigital number, since it uses as much as digits as its factorization.

21969437 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3138498.

The product of its digits is 81648, while the sum is 41.

The square root of 21969437 is about 4687.1566007549. The cubic root of 21969437 is about 280.0741172838.

The spelling of 21969437 in words is "twenty-one million, nine hundred sixty-nine thousand, four hundred thirty-seven".