21381710 has 64 divisors (see below), whose sum is σ = 46061568. Its totient is φ = 6994944.

The previous prime is 21381653. The next prime is 21381739. The reversal of 21381710 is 1718312.

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 31 ways as a sum of consecutive naturals, for example, 220382 + ... + 220478.

It is an arithmetic number, because the mean of its divisors is an integer number (719712).

Almost surely, 2^21381710 is an apocalyptic number.

21381710 is an abundant number, since it is smaller than the sum of its proper divisors (24679858).

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

21381710 is a wasteful number, since it uses less digits than its factorization.

21381710 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 21381710 is about 4624.0361157759. The cubic root of 21381710 is about 277.5539921456.

The spelling of 21381710 in words is "twenty-one million, three hundred eighty-one thousand, seven hundred ten".