21881772 has 96 divisors (see below), whose sum is σ = 62818560. Its totient is φ = 6531840.

The previous prime is 21881767. The next prime is 21881773. The reversal of 21881772 is 27718812.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21881773) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 134163 + ... + 134325.

It is an arithmetic number, because the mean of its divisors is an integer number (654360).

Almost surely, 2^21881772 is an apocalyptic number.

21881772 is a gapful number since it is divisible by the number (22) 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 21881772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31409280).

21881772 is an abundant number, since it is smaller than the sum of its proper divisors (40936788).

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

21881772 is a wasteful number, since it uses less digits than its factorization.

21881772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 300 (or 292 counting only the distinct ones).

The product of its digits is 12544, while the sum is 36.

The square root of 21881772 is about 4677.7956346980. The cubic root of 21881772 is about 279.7010925866.

The spelling of 21881772 in words is "twenty-one million, eight hundred eighty-one thousand, seven hundred seventy-two".