21367764 has 36 divisors (see below), whose sum is σ = 58924320. Its totient is φ = 6474960.

The previous prime is 21367763. The next prime is 21367771. The reversal of 21367764 is 46776312.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21367763) 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 11 ways as a sum of consecutive naturals, for example, 26584 + ... + 27375.

Almost surely, 2^21367764 is an apocalyptic number.

It is an amenable number.

21367764 is an abundant number, since it is smaller than the sum of its proper divisors (37556556).

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

21367764 is a wasteful number, since it uses less digits than its factorization.

21367764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53980 (or 53975 counting only the distinct ones).

The product of its digits is 42336, while the sum is 36.

The square root of 21367764 is about 4622.5278798510. The cubic root of 21367764 is about 277.4936351109.

The spelling of 21367764 in words is "twenty-one million, three hundred sixty-seven thousand, seven hundred sixty-four".