77969978 has 4 divisors (see below), whose sum is σ = 116954970. Its totient is φ = 38984988.

The previous prime is 77969971. The next prime is 77969981. The reversal of 77969978 is 87996977.

It is a happy number.

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., 56505289 + 21464689 = 7517^2 + 4633^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 77969978.

It is not an unprimeable number, because it can be changed into a prime (77969971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19492493 + ... + 19492496.

Almost surely, 2^77969978 is an apocalyptic number.

77969978 is a deficient number, since it is larger than the sum of its proper divisors (38984992).

77969978 is a wasteful number, since it uses less digits than its factorization.

77969978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38984991.

The product of its digits is 12002256, while the sum is 62.

The square root of 77969978 is about 8830.0610416916. The cubic root of 77969978 is about 427.2110432895.

The spelling of 77969978 in words is "seventy-seven million, nine hundred sixty-nine thousand, nine hundred seventy-eight".