21722172 has 48 divisors (see below), whose sum is σ = 52040352. Its totient is φ = 7050240.

The previous prime is 21722167. The next prime is 21722201. The reversal of 21722172 is 27122712.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 119922 + ... + 120102.

It is an arithmetic number, because the mean of its divisors is an integer number (1084174).

Almost surely, 2^21722172 is an apocalyptic number.

It is an amenable number.

21722172 is an abundant number, since it is smaller than the sum of its proper divisors (30318180).

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

21722172 is a wasteful number, since it uses less digits than its factorization.

21722172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398 (or 396 counting only the distinct ones).

The product of its digits is 784, while the sum is 24.

The square root of 21722172 is about 4660.7050968711. The cubic root of 21722172 is about 279.0194100138.

Adding to 21722172 its reverse (27122712), we get a palindrome (48844884).

It can be divided in two parts, 2172217 and 2, that multiplied together give a palindrome (4344434).

The spelling of 21722172 in words is "twenty-one million, seven hundred twenty-two thousand, one hundred seventy-two".