21881860 has 96 divisors (see below), whose sum is σ = 61754112. Its totient is φ = 6289920.

The previous prime is 21881857. The next prime is 21881891. The reversal of 21881860 is 6818812.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19474 + ... + 20566.

It is an arithmetic number, because the mean of its divisors is an integer number (643272).

Almost surely, 2^21881860 is an apocalyptic number.

21881860 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21881860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30877056).

21881860 is an abundant number, since it is smaller than the sum of its proper divisors (39872252).

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

21881860 is a wasteful number, since it uses less digits than its factorization.

21881860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1133 (or 1131 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 34.

The square root of 21881860 is about 4677.8050408284. The cubic root of 21881860 is about 279.7014675359.

The spelling of 21881860 in words is "twenty-one million, eight hundred eighty-one thousand, eight hundred sixty".