21423829 has 12 divisors (see below), whose sum is σ = 25005900. Its totient is φ = 18301248.

The previous prime is 21423827. The next prime is 21423863. The reversal of 21423829 is 92832412.

It can be written as a sum of positive squares in 2 ways, for example, as 15421329 + 6002500 = 3927^2 + 2450^2 .

It is not a de Polignac number, because 21423829 - 2¹ = 21423827 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21423829.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21423823) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19507 + ... + 20575.

It is an arithmetic number, because the mean of its divisors is an integer number (2083825).

Almost surely, 2^21423829 is an apocalyptic number.

It is an amenable number.

21423829 is a deficient number, since it is larger than the sum of its proper divisors (3582071).

21423829 is a wasteful number, since it uses less digits than its factorization.

21423829 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1492 (or 1485 counting only the distinct ones).

The product of its digits is 6912, while the sum is 31.

The square root of 21423829 is about 4628.5882296873. The cubic root of 21423829 is about 277.7361202182.

The spelling of 21423829 in words is "twenty-one million, four hundred twenty-three thousand, eight hundred twenty-nine".