21578679 has 6 divisors (see below), whose sum is σ = 31169216. Its totient is φ = 14385780.

The previous prime is 21578671. The next prime is 21578681. The reversal of 21578679 is 97687512.

21578679 is a `hidden beast` number, since 2 + 1 + 578 + 6 + 79 = 666.

It is not a de Polignac number, because 21578679 - 2³ = 21578671 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 (21578671) 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 5 ways as a sum of consecutive naturals, for example, 1198807 + ... + 1198824.

Almost surely, 2^21578679 is an apocalyptic number.

21578679 is a deficient number, since it is larger than the sum of its proper divisors (9590537).

21578679 is a wasteful number, since it uses less digits than its factorization.

21578679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2397637 (or 2397634 counting only the distinct ones).

The product of its digits is 211680, while the sum is 45.

The square root of 21578679 is about 4645.2856747460. The cubic root of 21578679 is about 278.4036671510.

The spelling of 21578679 in words is "twenty-one million, five hundred seventy-eight thousand, six hundred seventy-nine".