61577779 has 2 divisors, whose sum is σ = 61577780. Its totient is φ = 61577778.

The previous prime is 61577773. The next prime is 61577797. The reversal of 61577779 is 97777516.

Together with next prime (61577797) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61577779 is a prime.

It is not a weakly prime, because it can be changed into another prime (61577773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30788889 + 30788890.

It is an arithmetic number, because the mean of its divisors is an integer number (30788890).

Almost surely, 2^61577779 is an apocalyptic number.

61577779 is a deficient number, since it is larger than the sum of its proper divisors (1).

61577779 is an equidigital number, since it uses as much as digits as its factorization.

61577779 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 648270, while the sum is 49.

The square root of 61577779 is about 7847.1510116730. The cubic root of 61577779 is about 394.8886702219. Note that the first 3 decimals are identical.

The spelling of 61577779 in words is "sixty-one million, five hundred seventy-seven thousand, seven hundred seventy-nine".