21512227 has 6 divisors (see below), whose sum is σ = 23645804. Its totient is φ = 19556460.

The previous prime is 21512213. The next prime is 21512263. The reversal of 21512227 is 72221512.

It is a de Polignac number, because none of the positive numbers 2^k-21512227 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21512198 and 21512207.

It is not an unprimeable number, because it can be changed into a prime (21512027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 88773 + ... + 89014.

Almost surely, 2^21512227 is an apocalyptic number.

21512227 is a deficient number, since it is larger than the sum of its proper divisors (2133577).

21512227 is a wasteful number, since it uses less digits than its factorization.

21512227 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177809 (or 177798 counting only the distinct ones).

The product of its digits is 560, while the sum is 22.

The square root of 21512227 is about 4638.1275316662. The cubic root of 21512227 is about 278.1175899553.

Adding to 21512227 its reverse (72221512), we get a palindrome (93733739).

The spelling of 21512227 in words is "twenty-one million, five hundred twelve thousand, two hundred twenty-seven".