21739900178 has 4 divisors (see below), whose sum is σ = 32609850270. Its totient is φ = 10869950088.

The previous prime is 21739900163. The next prime is 21739900249. The reversal of 21739900178 is 87100993712.

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., 21711138409 + 28761769 = 147347^2 + 5363^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5434975043 + ... + 5434975046.

Almost surely, 2^21739900178 is an apocalyptic number.

21739900178 is a deficient number, since it is larger than the sum of its proper divisors (10869950092).

21739900178 is a wasteful number, since it uses less digits than its factorization.

21739900178 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10869950091.

The product of its (nonzero) digits is 190512, while the sum is 47.

The spelling of 21739900178 in words is "twenty-one billion, seven hundred thirty-nine million, nine hundred thousand, one hundred seventy-eight".