21722004 has 18 divisors (see below), whose sum is σ = 54908490. Its totient is φ = 7240656.

The previous prime is 21721981. The next prime is 21722011. The reversal of 21722004 is 40022712.

It can be written as a sum of positive squares in only one way, i.e., 16793604 + 4928400 = 4098^2 + 2220^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (18).

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 5 ways as a sum of consecutive naturals, for example, 301659 + ... + 301730.

Almost surely, 2^21722004 is an apocalyptic number.

It is an amenable number.

21722004 is an abundant number, since it is smaller than the sum of its proper divisors (33186486).

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

21722004 is a wasteful number, since it uses less digits than its factorization.

21722004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 603399 (or 603394 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 18.

The square root of 21722004 is about 4660.6870738122. The cubic root of 21722004 is about 279.0186906968.

Adding to 21722004 its reverse (40022712), we get a palindrome (61744716).

The spelling of 21722004 in words is "twenty-one million, seven hundred twenty-two thousand, four".