661899986268 has 24 divisors (see below), whose sum is σ = 1545741067920. Its totient is φ = 220446504960.

The previous prime is 661899986261. The next prime is 661899986269. The reversal of 661899986268 is 862689998166.

It is a super-2 number, since 2×661899986268² (a number of 24 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 661899986193 and 661899986202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661899986261) 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, 23338213 + ... + 23366556.

It is an arithmetic number, because the mean of its divisors is an integer number (64405877830).

Almost surely, 2^661899986268 is an apocalyptic number.

It is an amenable number.

661899986268 is an abundant number, since it is smaller than the sum of its proper divisors (883841081652).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661899986268 is a wasteful number, since it uses less digits than its factorization.

661899986268 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46705957 (or 46705955 counting only the distinct ones).

The product of its digits is 967458816, while the sum is 78.

The spelling of 661899986268 in words is "six hundred sixty-one billion, eight hundred ninety-nine million, nine hundred eighty-six thousand, two hundred sixty-eight".