78398781 has 16 divisors (see below), whose sum is σ = 110880000. Its totient is φ = 49102848.

The previous prime is 78398767. The next prime is 78398813. The reversal of 78398781 is 18789387.

It is not a de Polignac number, because 78398781 - 2⁶ = 78398717 is a prime.

It is a super-2 number, since 2×78398781² = 12292737724571922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78398701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38220 + ... + 40218.

It is an arithmetic number, because the mean of its divisors is an integer number (6930000).

Almost surely, 2^78398781 is an apocalyptic number.

It is an amenable number.

78398781 is a deficient number, since it is larger than the sum of its proper divisors (32481219).

78398781 is a wasteful number, since it uses less digits than its factorization.

78398781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2788.

The product of its digits is 677376, while the sum is 51.

The square root of 78398781 is about 8854.3086121955. The cubic root of 78398781 is about 427.9927739922.

The spelling of 78398781 in words is "seventy-eight million, three hundred ninety-eight thousand, seven hundred eighty-one".