21224987 has 24 divisors (see below), whose sum is σ = 25937280. Its totient is φ = 17297280.

The previous prime is 21224981. The next prime is 21224989. The reversal of 21224987 is 78942212.

It is not a de Polignac number, because 21224987 - 2⁴ = 21224971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21224981) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 135113 + ... + 135269.

It is an arithmetic number, because the mean of its divisors is an integer number (1080720).

Almost surely, 2^21224987 is an apocalyptic number.

21224987 is a deficient number, since it is larger than the sum of its proper divisors (4712293).

21224987 is a wasteful number, since it uses less digits than its factorization.

21224987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291 (or 284 counting only the distinct ones).

The product of its digits is 16128, while the sum is 35.

The square root of 21224987 is about 4607.0583890374. The cubic root of 21224987 is about 276.8741929362.

The spelling of 21224987 in words is "twenty-one million, two hundred twenty-four thousand, nine hundred eighty-seven".