21986237 has 16 divisors (see below), whose sum is σ = 27175680. Its totient is φ = 17321472.

The previous prime is 21986233. The next prime is 21986243. The reversal of 21986237 is 73268912.

It is not a de Polignac number, because 21986237 - 2² = 21986233 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21986237.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21986231) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32333 + ... + 33005.

It is an arithmetic number, because the mean of its divisors is an integer number (1698480).

Almost surely, 2^21986237 is an apocalyptic number.

It is an amenable number.

21986237 is a deficient number, since it is larger than the sum of its proper divisors (5189443).

21986237 is a wasteful number, since it uses less digits than its factorization.

21986237 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1052.

The product of its digits is 36288, while the sum is 38.

The square root of 21986237 is about 4688.9483895646. The cubic root of 21986237 is about 280.1454898656.

The spelling of 21986237 in words is "twenty-one million, nine hundred eighty-six thousand, two hundred thirty-seven".