77978401 has 2 divisors, whose sum is σ = 77978402. Its totient is φ = 77978400.

The previous prime is 77978399. The next prime is 77978429. The reversal of 77978401 is 10487977.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 41990400 + 35988001 = 6480^2 + 5999^2 .

It is a cyclic number.

It is not a de Polignac number, because 77978401 - 2¹ = 77978399 is a prime.

Together with 77978399, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (77978431) 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 as a sum of consecutive naturals, namely, 38989200 + 38989201.

It is an arithmetic number, because the mean of its divisors is an integer number (38989201).

Almost surely, 2^77978401 is an apocalyptic number.

It is an amenable number.

77978401 is a deficient number, since it is larger than the sum of its proper divisors (1).

77978401 is an equidigital number, since it uses as much as digits as its factorization.

77978401 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 98784, while the sum is 43.

The square root of 77978401 is about 8830.5379790815. The cubic root of 77978401 is about 427.2264264286.

The spelling of 77978401 in words is "seventy-seven million, nine hundred seventy-eight thousand, four hundred one".