21187494 has 20 divisors (see below), whose sum is σ = 47476044. Its totient is φ = 7062444.

The previous prime is 21187469. The next prime is 21187511. The reversal of 21187494 is 49478112.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 65232 + ... + 65555.

Almost surely, 2^21187494 is an apocalyptic number.

21187494 is an abundant number, since it is smaller than the sum of its proper divisors (26288550).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21187494 is a wasteful number, since it uses less digits than its factorization.

21187494 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130801 (or 130792 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 21187494 is about 4602.9875081299. The cubic root of 21187494 is about 276.7110681790.

The spelling of 21187494 in words is "twenty-one million, one hundred eighty-seven thousand, four hundred ninety-four".