61778557 has 4 divisors (see below), whose sum is σ = 65030080. Its totient is φ = 58527036.

The previous prime is 61778537. The next prime is 61778597. The reversal of 61778557 is 75587716.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61778557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61778537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1625733 + ... + 1625770.

It is an arithmetic number, because the mean of its divisors is an integer number (16257520).

Almost surely, 2^61778557 is an apocalyptic number.

It is an amenable number.

61778557 is a deficient number, since it is larger than the sum of its proper divisors (3251523).

61778557 is a wasteful number, since it uses less digits than its factorization.

61778557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3251522.

The product of its digits is 411600, while the sum is 46.

The square root of 61778557 is about 7859.9336511195. The cubic root of 61778557 is about 395.3173905783.

The spelling of 61778557 in words is "sixty-one million, seven hundred seventy-eight thousand, five hundred fifty-seven".