21131229 has 8 divisors (see below), whose sum is σ = 32200000. Its totient is φ = 12074976.

The previous prime is 21131191. The next prime is 21131251. The reversal of 21131229 is 92213112.

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

It is not a de Polignac number, because 21131229 - 2⁸ = 21130973 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 1006249 = 21131229 / (2 + 1 + 1 + 3 + 1 + 2 + 2 + 9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131269) 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, 503104 + ... + 503145.

It is an arithmetic number, because the mean of its divisors is an integer number (4025000).

Almost surely, 2^21131229 is an apocalyptic number.

It is an amenable number.

21131229 is a deficient number, since it is larger than the sum of its proper divisors (11068771).

21131229 is a wasteful number, since it uses less digits than its factorization.

21131229 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1006259.

The product of its digits is 216, while the sum is 21.

The square root of 21131229 is about 4596.8716536358. The cubic root of 21131229 is about 276.4659086161.

The spelling of 21131229 in words is "twenty-one million, one hundred thirty-one thousand, two hundred twenty-nine".