21031722 has 24 divisors (see below), whose sum is σ = 45726564. Its totient is φ = 6986304.

The previous prime is 21031721. The next prime is 21031739. The reversal of 21031722 is 22713012.

It can be written as a sum of positive squares in 2 ways, for example, as 18844281 + 2187441 = 4341^2 + 1479^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21031695 and 21031704.

It is not an unprimeable number, because it can be changed into a prime (21031721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3768 + ... + 7500.

Almost surely, 2^21031722 is an apocalyptic number.

21031722 is an abundant number, since it is smaller than the sum of its proper divisors (24694842).

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

21031722 is a wasteful number, since it uses less digits than its factorization.

21031722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4054 (or 4051 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21031722 is about 4586.0355428191. The cubic root of 21031722 is about 276.0312661492.

Adding to 21031722 its reverse (22713012), we get a palindrome (43744734).

The spelling of 21031722 in words is "twenty-one million, thirty-one thousand, seven hundred twenty-two".