21302720 has 28 divisors (see below), whose sum is σ = 50727864. Its totient is φ = 8520960.

The previous prime is 21302707. The next prime is 21302731. The reversal of 21302720 is 2720312.

21302720 = T₁₉₃ + T₁₉₄ + ... + T₅₁₂.

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, 32966 + ... + 33605.

Almost surely, 2^21302720 is an apocalyptic number.

21302720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21302720 is an abundant number, since it is smaller than the sum of its proper divisors (29425144).

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

21302720 is an equidigital number, since it uses as much as digits as its factorization.

21302720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66588 (or 66578 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 21302720 is about 4615.4869732240. The cubic root of 21302720 is about 277.2117831086.

It can be divided in two parts, 21302 and 720, that added together give a palindrome (22022).

The spelling of 21302720 in words is "twenty-one million, three hundred two thousand, seven hundred twenty".