21670420 has 24 divisors (see below), whose sum is σ = 45599400. Its totient is φ = 8650752.

The previous prime is 21670417. The next prime is 21670447. The reversal of 21670420 is 2407612.

It can be written as a sum of positive squares in 4 ways, for example, as 103684 + 21566736 = 322^2 + 4644^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21670391 and 21670400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14676 + ... + 16084.

It is an arithmetic number, because the mean of its divisors is an integer number (1899975).

Almost surely, 2^21670420 is an apocalyptic number.

21670420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21670420 is an abundant number, since it is smaller than the sum of its proper divisors (23928980).

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

21670420 is a wasteful number, since it uses less digits than its factorization.

21670420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2187 (or 2185 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 21670420 is about 4655.1498364714. The cubic root of 21670420 is about 278.7976504972.

The spelling of 21670420 in words is "twenty-one million, six hundred seventy thousand, four hundred twenty".