21940384 has 12 divisors (see below), whose sum is σ = 43195194. Its totient is φ = 10970176.

The previous prime is 21940381. The next prime is 21940397. The reversal of 21940384 is 48304912.

It can be written as a sum of positive squares in only one way, i.e., 21344400 + 595984 = 4620^2 + 772^2 .

It is not an unprimeable number, because it can be changed into a prime (21940381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342787 + ... + 342850.

Almost surely, 2^21940384 is an apocalyptic number.

It is an amenable number.

21940384 is a deficient number, since it is larger than the sum of its proper divisors (21254810).

21940384 is an equidigital number, since it uses as much as digits as its factorization.

21940384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 685647 (or 685639 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 21940384 is about 4684.0563617446. The cubic root of 21940384 is about 279.9506035311.

The spelling of 21940384 in words is "twenty-one million, nine hundred forty thousand, three hundred eighty-four".