21777804 has 18 divisors (see below), whose sum is σ = 55049540. Its totient is φ = 7259256.

The previous prime is 21777797. The next prime is 21777809. The reversal of 21777804 is 40877712.

It is a tau number, because it is divible by the number of its divisors (18).

It is a hoax number, since the sum of its digits (36) 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 (36), and also a Moran number because the ratio is a prime number: 604939 = 21777804 / (2 + 1 + 7 + 7 + 7 + 8 + 0 + 4).

It is not an unprimeable number, because it can be changed into a prime (21777809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 302434 + ... + 302505.

Almost surely, 2^21777804 is an apocalyptic number.

It is an amenable number.

21777804 is an abundant number, since it is smaller than the sum of its proper divisors (33271736).

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

21777804 is a wasteful number, since it uses less digits than its factorization.

21777804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 604949 (or 604944 counting only the distinct ones).

The product of its (nonzero) digits is 21952, while the sum is 36.

The square root of 21777804 is about 4666.6694761896. The cubic root of 21777804 is about 279.2574030241.

The spelling of 21777804 in words is "twenty-one million, seven hundred seventy-seven thousand, eight hundred four".