78391961 has 4 divisors (see below), whose sum is σ = 79153152. Its totient is φ = 77630772.

The previous prime is 78391949. The next prime is 78391979. The reversal of 78391961 is 16919387.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 78391961 - 2⁶ = 78391897 is a prime.

It is a super-2 number, since 2×78391961² = 12290599098851042, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (78391921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 380441 + ... + 380646.

It is an arithmetic number, because the mean of its divisors is an integer number (19788288).

Almost surely, 2^78391961 is an apocalyptic number.

It is an amenable number.

78391961 is a deficient number, since it is larger than the sum of its proper divisors (761191).

78391961 is a wasteful number, since it uses less digits than its factorization.

78391961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 761190.

The product of its digits is 81648, while the sum is 44.

The square root of 78391961 is about 8853.9234805819. The cubic root of 78391961 is about 427.9803631047.

The spelling of 78391961 in words is "seventy-eight million, three hundred ninety-one thousand, nine hundred sixty-one".