21851136 has 66 divisors (see below), whose sum is σ = 63121292. Its totient is φ = 7280640.

The previous prime is 21851119. The next prime is 21851153. The reversal of 21851136 is 63115812.

It is an interprime number because it is at equal distance from previous prime (21851119) and next prime (21851153).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8031 + ... + 10401.

Almost surely, 2^21851136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21851136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31560646).

21851136 is an abundant number, since it is smaller than the sum of its proper divisors (41270156).

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

21851136 is a wasteful number, since it uses less digits than its factorization.

21851136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2397 (or 2376 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 21851136 is about 4674.5198683929. The cubic root of 21851136 is about 279.5704979709.

Adding to 21851136 its reverse (63115812), we get a palindrome (84966948).

It can be divided in two parts, 2185 and 1136, that added together give a triangular number (3321 = T₈₁).

The spelling of 21851136 in words is "twenty-one million, eight hundred fifty-one thousand, one hundred thirty-six".