21386516 has 12 divisors (see below), whose sum is σ = 37501632. Its totient is φ = 10671768.

The previous prime is 21386503. The next prime is 21386531. The reversal of 21386516 is 61568312.

It is a happy number.

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, 3020 + ... + 7203.

It is an arithmetic number, because the mean of its divisors is an integer number (3125136).

Almost surely, 2^21386516 is an apocalyptic number.

It is an amenable number.

21386516 is a deficient number, since it is larger than the sum of its proper divisors (16115116).

21386516 is a wasteful number, since it uses less digits than its factorization.

21386516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10750 (or 10748 counting only the distinct ones).

The product of its digits is 8640, while the sum is 32.

The square root of 21386516 is about 4624.5557624490. Note that the first 3 decimals coincide. The cubic root of 21386516 is about 277.5747860009.

The spelling of 21386516 in words is "twenty-one million, three hundred eighty-six thousand, five hundred sixteen".