21740679 has 6 divisors (see below), whose sum is σ = 31403216. Its totient is φ = 14493780.

The previous prime is 21740669. The next prime is 21740683. The reversal of 21740679 is 97604712.

It is a happy number.

It is not a de Polignac number, because 21740679 - 2⁵ = 21740647 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21740639) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1207807 + ... + 1207824.

Almost surely, 2^21740679 is an apocalyptic number.

21740679 is a deficient number, since it is larger than the sum of its proper divisors (9662537).

21740679 is a wasteful number, since it uses less digits than its factorization.

21740679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2415637 (or 2415634 counting only the distinct ones).

The product of its (nonzero) digits is 21168, while the sum is 36.

The square root of 21740679 is about 4662.6901033631. The cubic root of 21740679 is about 279.0986277890.

The spelling of 21740679 in words is "twenty-one million, seven hundred forty thousand, six hundred seventy-nine".