61781805 has 16 divisors (see below), whose sum is σ = 109834560. Its totient is φ = 32950224.

The previous prime is 61781789. The next prime is 61781813. The reversal of 61781805 is 50818716.

It is not a de Polignac number, because 61781805 - 2⁴ = 61781789 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 61781805.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 228687 + ... + 228956.

It is an arithmetic number, because the mean of its divisors is an integer number (6864660).

Almost surely, 2^61781805 is an apocalyptic number.

It is an amenable number.

61781805 is a deficient number, since it is larger than the sum of its proper divisors (48052755).

61781805 is a wasteful number, since it uses less digits than its factorization.

61781805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 457657 (or 457651 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 36.

The square root of 61781805 is about 7860.1402659240. The cubic root of 61781805 is about 395.3243183779.

The spelling of 61781805 in words is "sixty-one million, seven hundred eighty-one thousand, eight hundred five".