21223131 has 8 divisors (see below), whose sum is σ = 28349520. Its totient is φ = 14122752.

The previous prime is 21223093. The next prime is 21223141. The reversal of 21223131 is 13132212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21223131 - 2¹⁴ = 21206747 is a prime.

It is a super-2 number, since 2×21223131² = 900842578886322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21223131.

It is not an unprimeable number, because it can be changed into a prime (21223141) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4510 + ... + 7923.

It is an arithmetic number, because the mean of its divisors is an integer number (3543690).

Almost surely, 2^21223131 is an apocalyptic number.

21223131 is a deficient number, since it is larger than the sum of its proper divisors (7126389).

21223131 is a wasteful number, since it uses less digits than its factorization.

21223131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13005.

The product of its digits is 72, while the sum is 15.

The square root of 21223131 is about 4606.8569545841. The cubic root of 21223131 is about 276.8661223623.

Adding to 21223131 its reverse (13132212), we get a palindrome (34355343).

It can be divided in two parts, 2122 and 3131, that added together give a triangular number (5253 = T₁₀₂).

The spelling of 21223131 in words is "twenty-one million, two hundred twenty-three thousand, one hundred thirty-one".