78139892 has 6 divisors (see below), whose sum is σ = 136744818. Its totient is φ = 39069944.

The previous prime is 78139883. The next prime is 78139903. The reversal of 78139892 is 29893187.

It can be written as a sum of positive squares in only one way, i.e., 52475536 + 25664356 = 7244^2 + 5066^2 .

It is a super-2 number, since 2×78139892² = 12211685443543328, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9767483 + ... + 9767490.

It is an arithmetic number, because the mean of its divisors is an integer number (22790803).

Almost surely, 2^78139892 is an apocalyptic number.

It is an amenable number.

78139892 is a deficient number, since it is larger than the sum of its proper divisors (58604926).

78139892 is a wasteful number, since it uses less digits than its factorization.

78139892 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19534977 (or 19534975 counting only the distinct ones).

The product of its digits is 217728, while the sum is 47.

The square root of 78139892 is about 8839.6771434255. The cubic root of 78139892 is about 427.5211475694.

The spelling of 78139892 in words is "seventy-eight million, one hundred thirty-nine thousand, eight hundred ninety-two".