667561989 has 8 divisors (see below), whose sum is σ = 891793152. Its totient is φ = 444186080.

The previous prime is 667561981. The next prime is 667562003. The reversal of 667561989 is 989165766.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 667561989 - 2³ = 667561981 is a prime.

It is a super-2 number, since 2×667561989² = 891278018315272242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667561981) 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, 211989 + ... + 215114.

It is an arithmetic number, because the mean of its divisors is an integer number (111474144).

Almost surely, 2^667561989 is an apocalyptic number.

It is an amenable number.

667561989 is a deficient number, since it is larger than the sum of its proper divisors (224231163).

667561989 is a wasteful number, since it uses less digits than its factorization.

667561989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 427627.

The product of its digits is 4898880, while the sum is 57.

The square root of 667561989 is about 25837.2209999450. The cubic root of 667561989 is about 873.9713578508.

The spelling of 667561989 in words is "six hundred sixty-seven million, five hundred sixty-one thousand, nine hundred eighty-nine".