21359780 has 24 divisors (see below), whose sum is σ = 48306552. Its totient is φ = 7886592.

The previous prime is 21359771. The next prime is 21359797. The reversal of 21359780 is 8795312.

It can be written as a sum of positive squares in 4 ways, for example, as 33856 + 21325924 = 184^2 + 4618^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21359780.

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, 40817 + ... + 41336.

It is an arithmetic number, because the mean of its divisors is an integer number (2012773).

Almost surely, 2^21359780 is an apocalyptic number.

21359780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21359780 is an abundant number, since it is smaller than the sum of its proper divisors (26946772).

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

21359780 is a wasteful number, since it uses less digits than its factorization.

21359780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82175 (or 82173 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 21359780 is about 4621.6642024275. The cubic root of 21359780 is about 277.4590692546.

The spelling of 21359780 in words is "twenty-one million, three hundred fifty-nine thousand, seven hundred eighty".