21527720 has 32 divisors (see below), whose sum is σ = 48577320. Its totient is φ = 8586240.

The previous prime is 21527713. The next prime is 21527749. The reversal of 21527720 is 2772512.

It can be written as a sum of positive squares in 4 ways, for example, as 19945156 + 1582564 = 4466^2 + 1258^2 .

It is a Smith number, since the sum of its digits (26) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21527720.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20324 + ... + 21356.

Almost surely, 2^21527720 is an apocalyptic number.

21527720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21527720 is an abundant number, since it is smaller than the sum of its proper divisors (27049600).

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

21527720 is a wasteful number, since it uses less digits than its factorization.

21527720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1565 (or 1561 counting only the distinct ones).

The product of its (nonzero) digits is 1960, while the sum is 26.

The square root of 21527720 is about 4639.7974093704. The cubic root of 21527720 is about 278.1843402399.

The spelling of 21527720 in words is "twenty-one million, five hundred twenty-seven thousand, seven hundred twenty".