21279942 has 16 divisors (see below), whose sum is σ = 47288880. Its totient is φ = 7093296.

The previous prime is 21279901. The next prime is 21279949. The reversal of 21279942 is 24997212.

It is a junction number, because it is equal to n+sod(n) for n = 21279897 and 21279906.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21279949) 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 7 ways as a sum of consecutive naturals, for example, 196983 + ... + 197090.

It is an arithmetic number, because the mean of its divisors is an integer number (2955555).

Almost surely, 2^21279942 is an apocalyptic number.

21279942 is an abundant number, since it is smaller than the sum of its proper divisors (26008938).

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

21279942 is a wasteful number, since it uses less digits than its factorization.

21279942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394084 (or 394078 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 21279942 is about 4613.0187513168. The cubic root of 21279942 is about 277.1129446837.

The spelling of 21279942 in words is "twenty-one million, two hundred seventy-nine thousand, nine hundred forty-two".