21497679 has 12 divisors (see below), whose sum is σ = 35488336. Its totient is φ = 12284352.

The previous prime is 21497677. The next prime is 21497689. The reversal of 21497679 is 97679412.

It is not a de Polignac number, because 21497679 - 2¹ = 21497677 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 (21497677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 170554 + ... + 170679.

Almost surely, 2^21497679 is an apocalyptic number.

21497679 is a deficient number, since it is larger than the sum of its proper divisors (13990657).

21497679 is a wasteful number, since it uses less digits than its factorization.

21497679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341246 (or 341243 counting only the distinct ones).

The product of its digits is 190512, while the sum is 45.

The square root of 21497679 is about 4636.5589611262. The cubic root of 21497679 is about 278.0548819411.

The spelling of 21497679 in words is "twenty-one million, four hundred ninety-seven thousand, six hundred seventy-nine".