21927881 has 16 divisors (see below), whose sum is σ = 24268800. Its totient is φ = 19731600.

The previous prime is 21927877. The next prime is 21927887. The reversal of 21927881 is 18872912.

It is a cyclic number.

It is not a de Polignac number, because 21927881 - 2² = 21927877 is a prime.

It is a super-2 number, since 2×21927881² = 961663930300322, which contains 22 as substring.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21927887) 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, 34436 + ... + 35066.

It is an arithmetic number, because the mean of its divisors is an integer number (1516800).

Almost surely, 2^21927881 is an apocalyptic number.

It is an amenable number.

21927881 is a deficient number, since it is larger than the sum of its proper divisors (2340919).

21927881 is a wasteful number, since it uses less digits than its factorization.

21927881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 740.

The product of its digits is 16128, while the sum is 38.

The square root of 21927881 is about 4682.7215377385. The cubic root of 21927881 is about 279.8974156518.

The spelling of 21927881 in words is "twenty-one million, nine hundred twenty-seven thousand, eight hundred eighty-one".