21851236 has 24 divisors (see below), whose sum is σ = 42293664. Its totient is φ = 9794880.

The previous prime is 21851233. The next prime is 21851251. The reversal of 21851236 is 63215812.

It is not an unprimeable number, because it can be changed into a prime (21851233) 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, 190 + ... + 6613.

It is an arithmetic number, because the mean of its divisors is an integer number (1762236).

Almost surely, 2^21851236 is an apocalyptic number.

It is an amenable number.

21851236 is a deficient number, since it is larger than the sum of its proper divisors (20442428).

21851236 is a wasteful number, since it uses less digits than its factorization.

21851236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6891 (or 6889 counting only the distinct ones).

The product of its digits is 2880, while the sum is 28.

The square root of 21851236 is about 4674.5305646664. The cubic root of 21851236 is about 279.5709244477.

The spelling of 21851236 in words is "twenty-one million, eight hundred fifty-one thousand, two hundred thirty-six".