21370636 has 12 divisors (see below), whose sum is σ = 42741328. Its totient is φ = 9158832.

The previous prime is 21370633. The next prime is 21370639. The reversal of 21370636 is 63607312.

It is an interprime number because it is at equal distance from previous prime (21370633) and next prime (21370639).

21370636 is an admirable number.

It is a Harshad number since it is a multiple of its sum of digits (28), and also a Moran number because the ratio is a prime number: 763237 = 21370636 / (2 + 1 + 3 + 7 + 0 + 6 + 3 + 6).

It is not an unprimeable number, because it can be changed into a prime (21370633) 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, 381591 + ... + 381646.

Almost surely, 2^21370636 is an apocalyptic number.

It is an amenable number.

21370636 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21370636 is a wasteful number, since it uses less digits than its factorization.

21370636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 763248 (or 763246 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 28.

The square root of 21370636 is about 4622.8385219473. The cubic root of 21370636 is about 277.5060670156.

Adding to 21370636 its reverse (63607312), we get a palindrome (84977948).

The spelling of 21370636 in words is "twenty-one million, three hundred seventy thousand, six hundred thirty-six".