21420867 has 16 divisors (see below), whose sum is σ = 32568480. Its totient is φ = 12406272.

The previous prime is 21420863. The next prime is 21420881. The reversal of 21420867 is 76802412.

It is not a de Polignac number, because 21420867 - 2² = 21420863 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21420863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15492 + ... + 16817.

It is an arithmetic number, because the mean of its divisors is an integer number (2035530).

Almost surely, 2^21420867 is an apocalyptic number.

21420867 is a deficient number, since it is larger than the sum of its proper divisors (11147613).

21420867 is a wasteful number, since it uses less digits than its factorization.

21420867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32342.

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 21420867 is about 4628.2682506527. The cubic root of 21420867 is about 277.7233199495.

The spelling of 21420867 in words is "twenty-one million, four hundred twenty thousand, eight hundred sixty-seven".