29131221 has 16 divisors (see below), whose sum is σ = 45120128. Its totient is φ = 16372800.

The previous prime is 29131187. The next prime is 29131243. The reversal of 29131221 is 12213192.

It is not a de Polignac number, because 29131221 - 2⁹ = 29130709 is a prime.

It is a super-3 number, since 3×29131221³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (29131261) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 10090 + ... + 12651.

It is an arithmetic number, because the mean of its divisors is an integer number (2820008).

Almost surely, 2^29131221 is an apocalyptic number.

29131221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

29131221 is a deficient number, since it is larger than the sum of its proper divisors (15988907).

29131221 is a wasteful number, since it uses less digits than its factorization.

29131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22812.

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

The square root of 29131221 is about 5397.3346199768. The cubic root of 29131221 is about 307.6943790518.

The spelling of 29131221 in words is "twenty-nine million, one hundred thirty-one thousand, two hundred twenty-one".