77998961 has 4 divisors (see below), whose sum is σ = 78803172. Its totient is φ = 77194752.

The previous prime is 77998939. The next prime is 77998969. The reversal of 77998961 is 16989977.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16989977 = 79 ⋅215063.

It can be written as a sum of positive squares in 2 ways, for example, as 38056561 + 39942400 = 6169^2 + 6320^2 .

It is a cyclic number.

It is not a de Polignac number, because 77998961 - 2²² = 73804657 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 77998897 and 77998906.

It is not an unprimeable number, because it can be changed into a prime (77998969) 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 3 ways as a sum of consecutive naturals, for example, 401960 + ... + 402153.

It is an arithmetic number, because the mean of its divisors is an integer number (19700793).

Almost surely, 2^77998961 is an apocalyptic number.

It is an amenable number.

77998961 is a deficient number, since it is larger than the sum of its proper divisors (804211).

77998961 is an equidigital number, since it uses as much as digits as its factorization.

77998961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 804210.

The product of its digits is 1714608, while the sum is 56.

The square root of 77998961 is about 8831.7020443400. The cubic root of 77998961 is about 427.2639710279.

The spelling of 77998961 in words is "seventy-seven million, nine hundred ninety-eight thousand, nine hundred sixty-one".