78061649 has 4 divisors (see below), whose sum is σ = 80753460. Its totient is φ = 75369840.

The previous prime is 78061631. The next prime is 78061651. The reversal of 78061649 is 94616087.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 94616087 = 641 ⋅147607.

It can be written as a sum of positive squares in 2 ways, for example, as 27196225 + 50865424 = 5215^2 + 7132^2 .

It is not a de Polignac number, because 78061649 - 2⁸ = 78061393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78061699) 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, 1345862 + ... + 1345919.

It is an arithmetic number, because the mean of its divisors is an integer number (20188365).

Almost surely, 2^78061649 is an apocalyptic number.

It is an amenable number.

78061649 is a deficient number, since it is larger than the sum of its proper divisors (2691811).

78061649 is a wasteful number, since it uses less digits than its factorization.

78061649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2691810.

The product of its (nonzero) digits is 72576, while the sum is 41.

The square root of 78061649 is about 8835.2503643077. The cubic root of 78061649 is about 427.3784048234.

The spelling of 78061649 in words is "seventy-eight million, sixty-one thousand, six hundred forty-nine".