21881792 has 28 divisors (see below), whose sum is σ = 44247816. Its totient is φ = 10732800.

The previous prime is 21881791. The next prime is 21881801. The reversal of 21881792 is 29718812.

It is a super-2 number, since 2×21881792² = 957625642262528, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21881791) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 167 + ... + 6617.

Almost surely, 2^21881792 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21881792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22123908).

21881792 is an abundant number, since it is smaller than the sum of its proper divisors (22366024).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21881792 is an equidigital number, since it uses as much as digits as its factorization.

21881792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6516 (or 6506 counting only the distinct ones).

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

The square root of 21881792 is about 4677.7977724566. The cubic root of 21881792 is about 279.7011778024.

The spelling of 21881792 in words is "twenty-one million, eight hundred eighty-one thousand, seven hundred ninety-two".