21919842 has 64 divisors (see below), whose sum is σ = 56309760. Its totient is φ = 6190992.

The previous prime is 21919831. The next prime is 21919847. The reversal of 21919842 is 24891912.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21919797 and 21919806.

It is not an unprimeable number, because it can be changed into a prime (21919847) 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, 38653 + ... + 39215.

It is an arithmetic number, because the mean of its divisors is an integer number (879840).

Almost surely, 2^21919842 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21919842, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28154880).

21919842 is an abundant number, since it is smaller than the sum of its proper divisors (34389918).

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

21919842 is a wasteful number, since it uses less digits than its factorization.

21919842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 684 (or 678 counting only the distinct ones).

The product of its digits is 10368, while the sum is 36.

The square root of 21919842 is about 4681.8630906937. The cubic root of 21919842 is about 279.8632069907.

The spelling of 21919842 in words is "twenty-one million, nine hundred nineteen thousand, eight hundred forty-two".