21225987 has 36 divisors (see below), whose sum is σ = 33329712. Its totient is φ = 12988800.

The previous prime is 21225973. The next prime is 21225989. The reversal of 21225987 is 78952212.

It is not a de Polignac number, because 21225987 - 2¹⁴ = 21209603 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21225989) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 347937 + ... + 347997.

Almost surely, 2^21225987 is an apocalyptic number.

21225987 is a deficient number, since it is larger than the sum of its proper divisors (12103725).

21225987 is a wasteful number, since it uses less digits than its factorization.

21225987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172 (or 128 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21225987 is about 4607.1669168807. The cubic root of 21225987 is about 276.8785411108.

The spelling of 21225987 in words is "twenty-one million, two hundred twenty-five thousand, nine hundred eighty-seven".