21474720 has 120 divisors (see below), whose sum is σ = 75833604. Its totient is φ = 5723136.

The previous prime is 21474707. The next prime is 21474737. The reversal of 21474720 is 2747412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20903184 + 571536 = 4572^2 + 756^2 .

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-2 number, since 2×21474720² = 922327198156800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 12132 + ... + 13788.

Almost surely, 2^21474720 is an apocalyptic number.

21474720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21474720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37916802).

21474720 is an abundant number, since it is smaller than the sum of its proper divisors (54358884).

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

21474720 is a wasteful number, since it uses less digits than its factorization.

21474720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1684 (or 1667 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 27.

The square root of 21474720 is about 4634.0824334489. The cubic root of 21474720 is about 277.9558613912.

The spelling of 21474720 in words is "twenty-one million, four hundred seventy-four thousand, seven hundred twenty".