21406715 has 24 divisors (see below), whose sum is σ = 28957824. Its totient is φ = 15171200.

The previous prime is 21406703. The next prime is 21406717. The reversal of 21406715 is 51760412.

It is not a de Polignac number, because 21406715 - 2⁴ = 21406699 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21406717) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 24374 + ... + 25236.

It is an arithmetic number, because the mean of its divisors is an integer number (1206576).

Almost surely, 2^21406715 is an apocalyptic number.

21406715 is a deficient number, since it is larger than the sum of its proper divisors (7551109).

21406715 is a wasteful number, since it uses less digits than its factorization.

21406715 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 931 (or 920 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 21406715 is about 4626.7391324776. The cubic root of 21406715 is about 277.6621458572.

The spelling of 21406715 in words is "twenty-one million, four hundred six thousand, seven hundred fifteen".