81388678802 has 4 divisors (see below), whose sum is σ = 122083018206. Its totient is φ = 40694339400.

The previous prime is 81388678759. The next prime is 81388678817. The reversal of 81388678802 is 20887688318.

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., 44432845681 + 36955833121 = 210791^2 + 192239^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20347169699 + ... + 20347169702.

Almost surely, 2^81388678802 is an apocalyptic number.

81388678802 is a deficient number, since it is larger than the sum of its proper divisors (40694339404).

81388678802 is a wasteful number, since it uses less digits than its factorization.

81388678802 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40694339403.

The product of its (nonzero) digits is 8257536, while the sum is 59.

The spelling of 81388678802 in words is "eighty-one billion, three hundred eighty-eight million, six hundred seventy-eight thousand, eight hundred two".