61666547751 has 16 divisors (see below), whose sum is σ = 92384344800. Its totient is φ = 40649108544.

The previous prime is 61666547743. The next prime is 61666547759. The reversal of 61666547751 is 15774566616.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (61666547743) and next prime (61666547759).

It is not a de Polignac number, because 61666547751 - 2³ = 61666547743 is a prime.

It is a super-2 number, since 2×61666547751² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61666547759) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12828756 + ... + 12833561.

It is an arithmetic number, because the mean of its divisors is an integer number (5774021550).

Almost surely, 2^61666547751 is an apocalyptic number.

61666547751 is a deficient number, since it is larger than the sum of its proper divisors (30717797049).

61666547751 is a wasteful number, since it uses less digits than its factorization.

61666547751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25662415 (or 25662409 counting only the distinct ones).

The product of its digits is 6350400, while the sum is 54.

The spelling of 61666547751 in words is "sixty-one billion, six hundred sixty-six million, five hundred forty-seven thousand, seven hundred fifty-one".