21893729 has 16 divisors (see below), whose sum is σ = 25859904. Its totient is φ = 18273600.

The previous prime is 21893699. The next prime is 21893747. The reversal of 21893729 is 92739812.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21893729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21893749) 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, 40199 + ... + 40739.

It is an arithmetic number, because the mean of its divisors is an integer number (1616244).

Almost surely, 2^21893729 is an apocalyptic number.

It is an amenable number.

21893729 is a deficient number, since it is larger than the sum of its proper divisors (3966175).

21893729 is a wasteful number, since it uses less digits than its factorization.

21893729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 848.

The product of its digits is 54432, while the sum is 41.

The square root of 21893729 is about 4679.0735194053. The cubic root of 21893729 is about 279.7520296098.

It can be divided in two parts, 21893 and 729, that added together give a palindrome (22622).

The spelling of 21893729 in words is "twenty-one million, eight hundred ninety-three thousand, seven hundred twenty-nine".