21936784 has 20 divisors (see below), whose sum is σ = 42686380. Its totient is φ = 10920960.

The previous prime is 21936781. The next prime is 21936787. The reversal of 21936784 is 48763912.

It is an interprime number because it is at equal distance from previous prime (21936781) and next prime (21936787).

It can be written as a sum of positive squares in 2 ways, for example, as 19114384 + 2822400 = 4372^2 + 1680^2 .

It is not an unprimeable number, because it can be changed into a prime (21936781) 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, 1012 + ... + 6700.

It is an arithmetic number, because the mean of its divisors is an integer number (2134319).

Almost surely, 2^21936784 is an apocalyptic number.

It is an amenable number.

21936784 is a deficient number, since it is larger than the sum of its proper divisors (20749596).

21936784 is a wasteful number, since it uses less digits than its factorization.

21936784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5938 (or 5932 counting only the distinct ones).

The product of its digits is 72576, while the sum is 40.

The square root of 21936784 is about 4683.6720636697. The cubic root of 21936784 is about 279.9352911692.

The spelling of 21936784 in words is "twenty-one million, nine hundred thirty-six thousand, seven hundred eighty-four".