661989167 has 6 divisors (see below), whose sum is σ = 770069088. Its totient is φ = 567419244.

The previous prime is 661989149. The next prime is 661989247. The reversal of 661989167 is 761989166.

It is not a de Polignac number, because 661989167 - 2¹⁴ = 661972783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661989667) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6754943 + ... + 6755040.

It is an arithmetic number, because the mean of its divisors is an integer number (128344848).

Almost surely, 2^661989167 is an apocalyptic number.

661989167 is a deficient number, since it is larger than the sum of its proper divisors (108079921).

661989167 is a wasteful number, since it uses less digits than its factorization.

661989167 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13509997 (or 13509990 counting only the distinct ones).

The product of its digits is 979776, while the sum is 53.

The square root of 661989167 is about 25729.1501414252. The cubic root of 661989167 is about 871.5325815897.

Subtracting 661989167 from its reverse (761989166), we obtain a palindrome (99999999).

The spelling of 661989167 in words is "six hundred sixty-one million, nine hundred eighty-nine thousand, one hundred sixty-seven".