61708781 has 8 divisors (see below), whose sum is σ = 64497720. Its totient is φ = 58963968.

The previous prime is 61708763. The next prime is 61708807. The reversal of 61708781 is 18780716.

It can be written as a sum of positive squares in 4 ways, for example, as 2280100 + 59428681 = 1510^2 + 7709^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61708781 is a prime.

It is a super-2 number, since 2×61708781² = 7615947305011922, 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 (61708981) 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 7 ways as a sum of consecutive naturals, for example, 8156 + ... + 13781.

It is an arithmetic number, because the mean of its divisors is an integer number (8062215).

Almost surely, 2^61708781 is an apocalyptic number.

It is an amenable number.

61708781 is a deficient number, since it is larger than the sum of its proper divisors (2788939).

61708781 is a wasteful number, since it uses less digits than its factorization.

61708781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22063.

The product of its (nonzero) digits is 18816, while the sum is 38.

The square root of 61708781 is about 7855.4936827675. The cubic root of 61708781 is about 395.1685036563.

The spelling of 61708781 in words is "sixty-one million, seven hundred eight thousand, seven hundred eighty-one".