21152020 has 24 divisors (see below), whose sum is σ = 45952200. Its totient is φ = 8168832.

The previous prime is 21152017. The next prime is 21152039. The reversal of 21152020 is 2025112.

It can be written as a sum of positive squares in 4 ways, for example, as 1331716 + 19820304 = 1154^2 + 4452^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17655 + ... + 18814.

It is an arithmetic number, because the mean of its divisors is an integer number (1914675).

Almost surely, 2^21152020 is an apocalyptic number.

21152020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21152020 is an abundant number, since it is smaller than the sum of its proper divisors (24800180).

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

21152020 is a wasteful number, since it uses less digits than its factorization.

21152020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36507 (or 36505 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21152020 is about 4599.1325269011. The cubic root of 21152020 is about 276.5565504269.

Adding to 21152020 its reverse (2025112), we get a palindrome (23177132).

The spelling of 21152020 in words is "twenty-one million, one hundred fifty-two thousand, twenty".