21508722 has 48 divisors (see below), whose sum is σ = 49907520. Its totient is φ = 6674400.

The previous prime is 21508717. The next prime is 21508763. The reversal of 21508722 is 22780512.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20347 + ... + 21377.

It is an arithmetic number, because the mean of its divisors is an integer number (1039740).

Almost surely, 2^21508722 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21508722, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24953760).

21508722 is an abundant number, since it is smaller than the sum of its proper divisors (28398798).

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

21508722 is a wasteful number, since it uses less digits than its factorization.

21508722 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1119 (or 1116 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 21508722 is about 4637.7496698291. The cubic root of 21508722 is about 278.1024845132.

The spelling of 21508722 in words is "twenty-one million, five hundred eight thousand, seven hundred twenty-two".