21279641 has 4 divisors (see below), whose sum is σ = 21407232. Its totient is φ = 21152052.

The previous prime is 21279637. The next prime is 21279653. The reversal of 21279641 is 14697212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21279641 - 2² = 21279637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21279598 and 21279607.

It is not an unprimeable number, because it can be changed into a prime (21279611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63545 + ... + 63878.

It is an arithmetic number, because the mean of its divisors is an integer number (5351808).

Almost surely, 2^21279641 is an apocalyptic number.

It is an amenable number.

21279641 is a deficient number, since it is larger than the sum of its proper divisors (127591).

21279641 is a wasteful number, since it uses less digits than its factorization.

21279641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127590.

The product of its digits is 6048, while the sum is 32.

The square root of 21279641 is about 4612.9861261443. The cubic root of 21279641 is about 277.1116381108. Note that the first 3 decimals are identical.

The spelling of 21279641 in words is "twenty-one million, two hundred seventy-nine thousand, six hundred forty-one".