21716729378 has 4 divisors (see below), whose sum is σ = 32575094070. Its totient is φ = 10858364688.

The previous prime is 21716729327. The next prime is 21716729389. The reversal of 21716729378 is 87392761712.

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., 14088977809 + 7627751569 = 118697^2 + 87337^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5429182343 + ... + 5429182346.

Almost surely, 2^21716729378 is an apocalyptic number.

21716729378 is a deficient number, since it is larger than the sum of its proper divisors (10858364692).

21716729378 is a wasteful number, since it uses less digits than its factorization.

21716729378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10858364691.

The product of its digits is 1778112, while the sum is 53.

The spelling of 21716729378 in words is "twenty-one billion, seven hundred sixteen million, seven hundred twenty-nine thousand, three hundred seventy-eight".