21701320 has 16 divisors (see below), whose sum is σ = 48828060. Its totient is φ = 8680512.

The previous prime is 21701297. The next prime is 21701371. The reversal of 21701320 is 2310712.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21696964 + 4356 = 4658^2 + 66^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21701294 and 21701303.

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, 271227 + ... + 271306.

Almost surely, 2^21701320 is an apocalyptic number.

21701320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21701320 is an abundant number, since it is smaller than the sum of its proper divisors (27126740).

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

21701320 is a wasteful number, since it uses less digits than its factorization.

21701320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 542544 (or 542540 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 21701320 is about 4658.4675591872. The cubic root of 21701320 is about 278.9301007217.

The spelling of 21701320 in words is "twenty-one million, seven hundred one thousand, three hundred twenty".