61477781 has 4 divisors (see below), whose sum is σ = 64150752. Its totient is φ = 58804812.

The previous prime is 61477777. The next prime is 61477783. The reversal of 61477781 is 18777416.

61477781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 61477781 - 2² = 61477777 is a prime.

It is a super-2 number, since 2×61477781² = 7559035113367922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61477783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1336451 + ... + 1336496.

It is an arithmetic number, because the mean of its divisors is an integer number (16037688).

Almost surely, 2^61477781 is an apocalyptic number.

It is an amenable number.

61477781 is a deficient number, since it is larger than the sum of its proper divisors (2672971).

61477781 is a wasteful number, since it uses less digits than its factorization.

61477781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2672970.

The product of its digits is 65856, while the sum is 41.

The square root of 61477781 is about 7840.7768110054. The cubic root of 61477781 is about 394.6747972281.

The spelling of 61477781 in words is "sixty-one million, four hundred seventy-seven thousand, seven hundred eighty-one".