21292428 has 12 divisors (see below), whose sum is σ = 49682360. Its totient is φ = 7097472.

The previous prime is 21292423. The next prime is 21292429. The reversal of 21292428 is 82429212.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 21292395 and 21292404.

It is not an unprimeable number, because it can be changed into a prime (21292423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 887173 + ... + 887196.

Almost surely, 2^21292428 is an apocalyptic number.

It is an amenable number.

21292428 is an abundant number, since it is smaller than the sum of its proper divisors (28389932).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21292428 is a wasteful number, since it uses less digits than its factorization.

21292428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1774376 (or 1774374 counting only the distinct ones).

The product of its digits is 4608, while the sum is 30.

The square root of 21292428 is about 4614.3718965857. The cubic root of 21292428 is about 277.1671327343.

The spelling of 21292428 in words is "twenty-one million, two hundred ninety-two thousand, four hundred twenty-eight".