61666217650 has 24 divisors (see below), whose sum is σ = 115987927860. Its totient is φ = 24389333760.

The previous prime is 61666217603. The next prime is 61666217659. The reversal of 61666217650 is 5671266616.

It can be written as a sum of positive squares in 6 ways, for example, as 21972429361 + 39693788289 = 148231^2 + 199233^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 61666217650.

It is not an unprimeable number, because it can be changed into a prime (61666217659) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6924339 + ... + 6933238.

Almost surely, 2^61666217650 is an apocalyptic number.

61666217650 is a deficient number, since it is larger than the sum of its proper divisors (54321710210).

61666217650 is a wasteful number, since it uses less digits than its factorization.

61666217650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13857678 (or 13857673 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 46.

The spelling of 61666217650 in words is "sixty-one billion, six hundred sixty-six million, two hundred seventeen thousand, six hundred fifty".