78051557 has 4 divisors (see below), whose sum is σ = 80743020. Its totient is φ = 75360096.

The previous prime is 78051551. The next prime is 78051569. The reversal of 78051557 is 75515087.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 63504961 + 14546596 = 7969^2 + 3814^2 .

It is a de Polignac number, because none of the positive numbers 2^k-78051557 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 78051557.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78051551) 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, 1345688 + ... + 1345745.

It is an arithmetic number, because the mean of its divisors is an integer number (20185755).

Almost surely, 2^78051557 is an apocalyptic number.

It is an amenable number.

78051557 is a deficient number, since it is larger than the sum of its proper divisors (2691463).

78051557 is a wasteful number, since it uses less digits than its factorization.

78051557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2691462.

The product of its (nonzero) digits is 49000, while the sum is 38.

The square root of 78051557 is about 8834.6792245106. The cubic root of 78051557 is about 427.3599865229.

The spelling of 78051557 in words is "seventy-eight million, fifty-one thousand, five hundred fifty-seven".