61157781 has 32 divisors (see below), whose sum is σ = 96307200. Its totient is φ = 38283840.

The previous prime is 61157779. The next prime is 61157783. The reversal of 61157781 is 18775116.

It is a happy number.

61157781 is a `hidden beast` number, since 6 + 1 + 1 + 577 + 81 = 666.

61157781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (61157779) and next prime (61157783).

It is not a de Polignac number, because 61157781 - 2¹ = 61157779 is a prime.

It is a super-2 number, since 2×61157781² = 7480548353687922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61157783) 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 31 ways as a sum of consecutive naturals, for example, 27916 + ... + 30026.

It is an arithmetic number, because the mean of its divisors is an integer number (3009600).

Almost surely, 2^61157781 is an apocalyptic number.

It is an amenable number.

61157781 is a deficient number, since it is larger than the sum of its proper divisors (35149419).

61157781 is a wasteful number, since it uses less digits than its factorization.

61157781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2186 (or 2180 counting only the distinct ones).

The product of its digits is 11760, while the sum is 36.

The square root of 61157781 is about 7820.3440461402. The cubic root of 61157781 is about 393.9888274465.

The spelling of 61157781 in words is "sixty-one million, one hundred fifty-seven thousand, seven hundred eighty-one".