21901968 has 120 divisors (see below), whose sum is σ = 69266400. Its totient is φ = 6621120.

The previous prime is 21901909. The next prime is 21901969. The reversal of 21901968 is 86910912.

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 (21901969) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 52063 + ... + 52481.

It is an arithmetic number, because the mean of its divisors is an integer number (577220).

Almost surely, 2^21901968 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 21901968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34633200).

21901968 is an abundant number, since it is smaller than the sum of its proper divisors (47364432).

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

21901968 is a wasteful number, since it uses less digits than its factorization.

21901968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 458 (or 435 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 21901968 is about 4679.9538459263. The cubic root of 21901968 is about 279.7871170985.

The spelling of 21901968 in words is "twenty-one million, nine hundred one thousand, nine hundred sixty-eight".