21366780 has 24 divisors (see below), whose sum is σ = 59827152. Its totient is φ = 5697792.

The previous prime is 21366767. The next prime is 21366803. The reversal of 21366780 is 8766312.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 177997 + ... + 178116.

It is an arithmetic number, because the mean of its divisors is an integer number (2492798).

Almost surely, 2^21366780 is an apocalyptic number.

21366780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21366780 is an abundant number, since it is smaller than the sum of its proper divisors (38460372).

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

21366780 is a wasteful number, since it uses less digits than its factorization.

21366780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356125 (or 356123 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 33.

The square root of 21366780 is about 4622.4214433563. The cubic root of 21366780 is about 277.4893754556.

The spelling of 21366780 in words is "twenty-one million, three hundred sixty-six thousand, seven hundred eighty".