21715420 has 12 divisors (see below), whose sum is σ = 45602424. Its totient is φ = 8686160.

The previous prime is 21715361. The next prime is 21715433. The reversal of 21715420 is 2451712.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21715391 and 21715400.

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, 542866 + ... + 542905.

It is an arithmetic number, because the mean of its divisors is an integer number (3800202).

Almost surely, 2^21715420 is an apocalyptic number.

21715420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21715420 is an abundant number, since it is smaller than the sum of its proper divisors (23887004).

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

21715420 is a wasteful number, since it uses less digits than its factorization.

21715420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1085780 (or 1085778 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 21715420 is about 4659.9806866553. The cubic root of 21715420 is about 278.9904974003.

The spelling of 21715420 in words is "twenty-one million, seven hundred fifteen thousand, four hundred twenty".