21513478 has 8 divisors (see below), whose sum is σ = 36880272. Its totient is φ = 9220056.

The previous prime is 21513469. The next prime is 21513511. The reversal of 21513478 is 87431512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 768325 + ... + 768352.

It is an arithmetic number, because the mean of its divisors is an integer number (4610034).

Almost surely, 2^21513478 is an apocalyptic number.

21513478 is a deficient number, since it is larger than the sum of its proper divisors (15366794).

21513478 is a wasteful number, since it uses less digits than its factorization.

21513478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1536686.

The product of its digits is 6720, while the sum is 31.

The square root of 21513478 is about 4638.2623901629. The cubic root of 21513478 is about 278.1229809726.

The spelling of 21513478 in words is "twenty-one million, five hundred thirteen thousand, four hundred seventy-eight".