21642884478 has 32 divisors (see below), whose sum is σ = 48296563200. Its totient is φ = 7184105208.

The previous prime is 21642884449. The next prime is 21642884479. The reversal of 21642884478 is 87448824612.

21642884478 is a `hidden beast` number, since 2 + 164 + 2 + 8 + 8 + 4 + 478 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642884479) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 825576 + ... + 851387.

It is an arithmetic number, because the mean of its divisors is an integer number (1509267600).

Almost surely, 2^21642884478 is an apocalyptic number.

21642884478 is an abundant number, since it is smaller than the sum of its proper divisors (26653678722).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21642884478 is a wasteful number, since it uses less digits than its factorization.

21642884478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1677213 (or 1677207 counting only the distinct ones).

The product of its digits is 5505024, while the sum is 54.

The spelling of 21642884478 in words is "twenty-one billion, six hundred forty-two million, eight hundred eighty-four thousand, four hundred seventy-eight".