667661293 has 4 divisors (see below), whose sum is σ = 719019868. Its totient is φ = 616302720.

The previous prime is 667661249. The next prime is 667661327. The reversal of 667661293 is 392166766.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 392166766 = 2 ⋅196083383.

It can be written as a sum of positive squares in 2 ways, for example, as 103266244 + 564395049 = 10162^2 + 23757^2 .

It is a cyclic number.

It is not a de Polignac number, because 667661293 - 2¹⁷ = 667530221 is a prime.

It is a super-3 number, since 3×667661293³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667661233) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25679268 + ... + 25679293.

It is an arithmetic number, because the mean of its divisors is an integer number (179754967).

Almost surely, 2^667661293 is an apocalyptic number.

It is an amenable number.

667661293 is a deficient number, since it is larger than the sum of its proper divisors (51358575).

667661293 is a wasteful number, since it uses less digits than its factorization.

667661293 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51358574.

The product of its digits is 489888, while the sum is 46.

The square root of 667661293 is about 25839.1426521857. The cubic root of 667661293 is about 874.0146919282.

The spelling of 667661293 in words is "six hundred sixty-seven million, six hundred sixty-one thousand, two hundred ninety-three".