21945693 has 16 divisors (see below), whose sum is σ = 36481536. Its totient is φ = 11400240.

The previous prime is 21945689. The next prime is 21945751. The reversal of 21945693 is 39654912.

It is not a de Polignac number, because 21945693 - 2² = 21945689 is a prime.

It is a super-2 number, since 2×21945693² = 963226882500498, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21945643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47271 + ... + 47732.

It is an arithmetic number, because the mean of its divisors is an integer number (2280096).

Almost surely, 2^21945693 is an apocalyptic number.

It is an amenable number.

21945693 is a deficient number, since it is larger than the sum of its proper divisors (14535843).

21945693 is a wasteful number, since it uses less digits than its factorization.

21945693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95024.

The product of its digits is 58320, while the sum is 39.

The square root of 21945693 is about 4684.6230371290. The cubic root of 21945693 is about 279.9731819553.

It can be divided in two parts, 2194 and 5693, that added together give a palindrome (7887).

The spelling of 21945693 in words is "twenty-one million, nine hundred forty-five thousand, six hundred ninety-three".