21151236 has 12 divisors (see below), whose sum is σ = 49352912. Its totient is φ = 7050408.

The previous prime is 21151219. The next prime is 21151241. The reversal of 21151236 is 63215112.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 881290 + ... + 881313.

Almost surely, 2^21151236 is an apocalyptic number.

It is an amenable number.

21151236 is an abundant number, since it is smaller than the sum of its proper divisors (28201676).

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

21151236 is a wasteful number, since it uses less digits than its factorization.

21151236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1762610 (or 1762608 counting only the distinct ones).

The product of its digits is 360, while the sum is 21.

The square root of 21151236 is about 4599.0472926466. The cubic root of 21151236 is about 276.5531335268.

Adding to 21151236 its reverse (63215112), we get a palindrome (84366348).

The spelling of 21151236 in words is "twenty-one million, one hundred fifty-one thousand, two hundred thirty-six".