21704420 has 12 divisors (see below), whose sum is σ = 45579324. Its totient is φ = 8681760.

The previous prime is 21704411. The next prime is 21704443. The reversal of 21704420 is 2440712.

It can be written as a sum of positive squares in 2 ways, for example, as 13897984 + 7806436 = 3728^2 + 2794^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 1085221 = 21704420 / (2 + 1 + 7 + 0 + 4 + 4 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 21704392 and 21704401.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 542591 + ... + 542630.

It is an arithmetic number, because the mean of its divisors is an integer number (3798277).

Almost surely, 2^21704420 is an apocalyptic number.

21704420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21704420 is an abundant number, since it is smaller than the sum of its proper divisors (23874904).

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

21704420 is a wasteful number, since it uses less digits than its factorization.

21704420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1085230 (or 1085228 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 20.

The square root of 21704420 is about 4658.8002747489. The cubic root of 21704420 is about 278.9433816672.

The spelling of 21704420 in words is "twenty-one million, seven hundred four thousand, four hundred twenty".