21978478479 has 16 divisors (see below), whose sum is σ = 29449244160. Its totient is φ = 14580108480.

The previous prime is 21978478477. The next prime is 21978478481. The reversal of 21978478479 is 97487487912.

It is an interprime number because it is at equal distance from previous prime (21978478477) and next prime (21978478481).

It is not a de Polignac number, because 21978478479 - 2¹ = 21978478477 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21978478477) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1012419 + ... + 1033899.

It is an arithmetic number, because the mean of its divisors is an integer number (1840577760).

Almost surely, 2^21978478479 is an apocalyptic number.

21978478479 is a deficient number, since it is larger than the sum of its proper divisors (7470765681).

21978478479 is a wasteful number, since it uses less digits than its factorization.

21978478479 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23150.

The product of its digits is 56899584, while the sum is 66.

The spelling of 21978478479 in words is "twenty-one billion, nine hundred seventy-eight million, four hundred seventy-eight thousand, four hundred seventy-nine".