21415780 has 12 divisors (see below), whose sum is σ = 44973180. Its totient is φ = 8566304.

The previous prime is 21415777. The next prime is 21415781. The reversal of 21415780 is 8751412.

It can be written as a sum of positive squares in 2 ways, for example, as 14561856 + 6853924 = 3816^2 + 2618^2 .

It is not an unprimeable number, because it can be changed into a prime (21415781) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 535375 + ... + 535414.

It is an arithmetic number, because the mean of its divisors is an integer number (3747765).

Almost surely, 2^21415780 is an apocalyptic number.

21415780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21415780 is an abundant number, since it is smaller than the sum of its proper divisors (23557400).

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

21415780 is a wasteful number, since it uses less digits than its factorization.

21415780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1070798 (or 1070796 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 21415780 is about 4627.7186604201. The cubic root of 21415780 is about 277.7013337498.

It can be divided in two parts, 2141 and 5780, that added together give a square (7921 = 89²).

The spelling of 21415780 in words is "twenty-one million, four hundred fifteen thousand, seven hundred eighty".