661691473 has 8 divisors (see below), whose sum is σ = 697100000. Its totient is φ = 626341248.

The previous prime is 661691453. The next prime is 661691477. The reversal of 661691473 is 374196166.

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 661691473 - 2²¹ = 659594321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661691477) 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, 9790 + ... + 37672.

It is an arithmetic number, because the mean of its divisors is an integer number (87137500).

Almost surely, 2^661691473 is an apocalyptic number.

It is an amenable number.

661691473 is a deficient number, since it is larger than the sum of its proper divisors (35408527).

661691473 is a wasteful number, since it uses less digits than its factorization.

661691473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29151.

The product of its digits is 163296, while the sum is 43.

The square root of 661691473 is about 25723.3643406145. The cubic root of 661691473 is about 871.4019203774.

It can be divided in two parts, 6616 and 91473, that added together give a palindrome (98089).

The spelling of 661691473 in words is "six hundred sixty-one million, six hundred ninety-one thousand, four hundred seventy-three".