21618429 has 32 divisors (see below), whose sum is σ = 33976320. Its totient is φ = 11973312.

The previous prime is 21618403. The next prime is 21618451. The reversal of 21618429 is 92481612.

It is not a de Polignac number, because 21618429 - 2⁷ = 21618301 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21618429.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21618479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 137619 + ... + 137775.

It is an arithmetic number, because the mean of its divisors is an integer number (1061760).

Almost surely, 2^21618429 is an apocalyptic number.

It is an amenable number.

21618429 is a deficient number, since it is larger than the sum of its proper divisors (12357891).

21618429 is a wasteful number, since it uses less digits than its factorization.

21618429 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329.

The product of its digits is 6912, while the sum is 33.

The square root of 21618429 is about 4649.5622374585. The cubic root of 21618429 is about 278.5745110582.

The spelling of 21618429 in words is "twenty-one million, six hundred eighteen thousand, four hundred twenty-nine".