21675987 has 12 divisors (see below), whose sum is σ = 31351320. Its totient is φ = 14431488.

The previous prime is 21675949. The next prime is 21676007. The reversal of 21675987 is 78957612.

It is not a de Polignac number, because 21675987 - 2¹² = 21671891 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21675917) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9964 + ... + 11942.

It is an arithmetic number, because the mean of its divisors is an integer number (2612610).

Almost surely, 2^21675987 is an apocalyptic number.

21675987 is a deficient number, since it is larger than the sum of its proper divisors (9675333).

21675987 is a wasteful number, since it uses less digits than its factorization.

21675987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3202 (or 3199 counting only the distinct ones).

The product of its digits is 211680, while the sum is 45.

The square root of 21675987 is about 4655.7477380116. The cubic root of 21675987 is about 278.8215222639.

The spelling of 21675987 in words is "twenty-one million, six hundred seventy-five thousand, nine hundred eighty-seven".