21939229 has 4 divisors (see below), whose sum is σ = 23626876. Its totient is φ = 20251584.

The previous prime is 21939179. The next prime is 21939233. The reversal of 21939229 is 92293912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9703225 + 12236004 = 3115^2 + 3498^2 .

It is a cyclic number.

It is not a de Polignac number, because 21939229 - 2⁷ = 21939101 is a prime.

It is a super-2 number, since 2×21939229² = 962659538228882, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21939529) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 843804 + ... + 843829.

It is an arithmetic number, because the mean of its divisors is an integer number (5906719).

Almost surely, 2^21939229 is an apocalyptic number.

It is an amenable number.

21939229 is a deficient number, since it is larger than the sum of its proper divisors (1687647).

21939229 is a wasteful number, since it uses less digits than its factorization.

21939229 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1687646.

The product of its digits is 17496, while the sum is 37.

The square root of 21939229 is about 4683.9330695474. The cubic root of 21939229 is about 279.9456909975.

The spelling of 21939229 in words is "twenty-one million, nine hundred thirty-nine thousand, two hundred twenty-nine".