21432987 has 24 divisors (see below), whose sum is σ = 33007104. Its totient is φ = 13370544.

The previous prime is 21432979. The next prime is 21432991. The reversal of 21432987 is 78923412.

It is not a de Polignac number, because 21432987 - 2³ = 21432979 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21432967) 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, 8628 + ... + 10830.

It is an arithmetic number, because the mean of its divisors is an integer number (1375296).

Almost surely, 2^21432987 is an apocalyptic number.

21432987 is a deficient number, since it is larger than the sum of its proper divisors (11574117).

21432987 is a wasteful number, since it uses less digits than its factorization.

21432987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2279 (or 2276 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21432987 is about 4629.5774105203. The cubic root of 21432987 is about 277.7756890095.

The spelling of 21432987 in words is "twenty-one million, four hundred thirty-two thousand, nine hundred eighty-seven".