21940689 has 16 divisors (see below), whose sum is σ = 30643200. Its totient is φ = 13937616.

The previous prime is 21940679. The next prime is 21940703. The reversal of 21940689 is 98604912.

It is not a de Polignac number, because 21940689 - 2⁵ = 21940657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21940679) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 25732 + ... + 26570.

It is an arithmetic number, because the mean of its divisors is an integer number (1915200).

Almost surely, 2^21940689 is an apocalyptic number.

It is an amenable number.

21940689 is a deficient number, since it is larger than the sum of its proper divisors (8702511).

21940689 is a wasteful number, since it uses less digits than its factorization.

21940689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1244.

The product of its (nonzero) digits is 31104, while the sum is 39.

The square root of 21940689 is about 4684.0889188827. The cubic root of 21940689 is about 279.9519007514.

The spelling of 21940689 in words is "twenty-one million, nine hundred forty thousand, six hundred eighty-nine".