667561394 has 8 divisors (see below), whose sum is σ = 1020235500. Its totient is φ = 327482896.

The previous prime is 667561387. The next prime is 667561481. The reversal of 667561394 is 493165766.

It can be written as a sum of positive squares in 2 ways, for example, as 635695369 + 31866025 = 25213^2 + 5645^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3148769 + ... + 3148980.

Almost surely, 2^667561394 is an apocalyptic number.

667561394 is a deficient number, since it is larger than the sum of its proper divisors (352674106).

667561394 is a wasteful number, since it uses less digits than its factorization.

667561394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6297804.

The product of its digits is 816480, while the sum is 47.

The square root of 667561394 is about 25837.2094855462. The cubic root of 667561394 is about 873.9710981930.

The spelling of 667561394 in words is "six hundred sixty-seven million, five hundred sixty-one thousand, three hundred ninety-four".