660378781666 has 16 divisors (see below), whose sum is σ = 1034694393984. Its totient is φ = 315510040384.

The previous prime is 660378781663. The next prime is 660378781691. The reversal of 660378781666 is 666187873066.

It is a super-2 number, since 2×660378781666² (a number of 24 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 660378781598 and 660378781607.

It is not an unprimeable number, because it can be changed into a prime (660378781663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7302070 + ... + 7391953.

It is an arithmetic number, because the mean of its divisors is an integer number (64668399624).

Almost surely, 2^660378781666 is an apocalyptic number.

660378781666 is a deficient number, since it is larger than the sum of its proper divisors (374315612318).

660378781666 is a wasteful number, since it uses less digits than its factorization.

660378781666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14695025.

The product of its (nonzero) digits is 73156608, while the sum is 64.

The spelling of 660378781666 in words is "six hundred sixty billion, three hundred seventy-eight million, seven hundred eighty-one thousand, six hundred sixty-six".