21945237 has 8 divisors (see below), whose sum is σ = 29339040. Its totient is φ = 14590800.

The previous prime is 21945229. The next prime is 21945239. The reversal of 21945237 is 73254912.

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

It is not a de Polignac number, because 21945237 - 2³ = 21945229 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21945198 and 21945207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21945239) 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, 8514 + ... + 10787.

It is an arithmetic number, because the mean of its divisors is an integer number (3667380).

Almost surely, 2^21945237 is an apocalyptic number.

It is an amenable number.

21945237 is a deficient number, since it is larger than the sum of its proper divisors (7393803).

21945237 is a wasteful number, since it uses less digits than its factorization.

21945237 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19683.

The product of its digits is 15120, while the sum is 33.

The square root of 21945237 is about 4684.5743670050. The cubic root of 21945237 is about 279.9712427949.

The spelling of 21945237 in words is "twenty-one million, nine hundred forty-five thousand, two hundred thirty-seven".