21752820 has 48 divisors (see below), whose sum is σ = 67677120. Its totient is φ = 5800608.

The previous prime is 21752791. The next prime is 21752831. The reversal of 21752820 is 2825712.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19602 + ... + 20681.

It is an arithmetic number, because the mean of its divisors is an integer number (1409940).

Almost surely, 2^21752820 is an apocalyptic number.

21752820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21752820 is an abundant number, since it is smaller than the sum of its proper divisors (45924300).

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

21752820 is a wasteful number, since it uses less digits than its factorization.

21752820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40301 (or 40293 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 21752820 is about 4663.9918524800. The cubic root of 21752820 is about 279.1505719787.

The spelling of 21752820 in words is "twenty-one million, seven hundred fifty-two thousand, eight hundred twenty".