21945084178 has 4 divisors (see below), whose sum is σ = 32917626270. Its totient is φ = 10972542088.

The previous prime is 21945084169. The next prime is 21945084181. The reversal of 21945084178 is 87148054912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 13561301209 + 8383782969 = 116453^2 + 91563^2 .

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5486271043 + ... + 5486271046.

Almost surely, 2^21945084178 is an apocalyptic number.

21945084178 is a deficient number, since it is larger than the sum of its proper divisors (10972542092).

21945084178 is a wasteful number, since it uses less digits than its factorization.

21945084178 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10972542091.

The product of its (nonzero) digits is 645120, while the sum is 49.

The spelling of 21945084178 in words is "twenty-one billion, nine hundred forty-five million, eighty-four thousand, one hundred seventy-eight".