21788380 has 24 divisors (see below), whose sum is σ = 45870048. Its totient is φ = 8693568.

The previous prime is 21788369. The next prime is 21788399. The reversal of 21788380 is 8388712.

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, 8622 + ... + 10858.

It is an arithmetic number, because the mean of its divisors is an integer number (1911252).

Almost surely, 2^21788380 is an apocalyptic number.

21788380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21788380 is an abundant number, since it is smaller than the sum of its proper divisors (24081668).

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

21788380 is a wasteful number, since it uses less digits than its factorization.

21788380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2733 (or 2731 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 37.

The square root of 21788380 is about 4667.8024808254. The cubic root of 21788380 is about 279.3026011585.

The spelling of 21788380 in words is "twenty-one million, seven hundred eighty-eight thousand, three hundred eighty".