78401939 has 8 divisors (see below), whose sum is σ = 97747968. Its totient is φ = 61092360.

The previous prime is 78401887. The next prime is 78401951. The reversal of 78401939 is 93910487.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 78401939 - 2²⁴ = 61624723 is a prime.

It is a super-2 number, since 2×78401939² = 12293728077919442, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 78401896 and 78401905.

It is not an unprimeable number, because it can be changed into a prime (78401539) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 509027 + ... + 509180.

It is an arithmetic number, because the mean of its divisors is an integer number (12218496).

Almost surely, 2^78401939 is an apocalyptic number.

78401939 is a deficient number, since it is larger than the sum of its proper divisors (19346029).

78401939 is a wasteful number, since it uses less digits than its factorization.

78401939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1018225.

The product of its (nonzero) digits is 54432, while the sum is 41.

The square root of 78401939 is about 8854.4869416584. The cubic root of 78401939 is about 427.9985206080.

It can be divided in two parts, 7840 and 1939, that added together give a palindrome (9779).

The spelling of 78401939 in words is "seventy-eight million, four hundred one thousand, nine hundred thirty-nine".