21279420 has 36 divisors (see below), whose sum is σ = 64548120. Its totient is φ = 5674464.

The previous prime is 21279409. The next prime is 21279421. The reversal of 21279420 is 2497212.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21279421) 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, 58930 + ... + 59289.

Almost surely, 2^21279420 is an apocalyptic number.

21279420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21279420 is an abundant number, since it is smaller than the sum of its proper divisors (43268700).

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

21279420 is a wasteful number, since it uses less digits than its factorization.

21279420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118234 (or 118229 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21279420 is about 4612.9621719672. The cubic root of 21279420 is about 277.1106787919.

The spelling of 21279420 in words is "twenty-one million, two hundred seventy-nine thousand, four hundred twenty".