661181397 has 8 divisors (see below), whose sum is σ = 885529344. Its totient is φ = 438810528.

The previous prime is 661181387. The next prime is 661181401. The reversal of 661181397 is 793181166.

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

It is not a de Polignac number, because 661181397 - 2⁶ = 661181333 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661181347) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 493488 + ... + 494825.

It is an arithmetic number, because the mean of its divisors is an integer number (110691168).

Almost surely, 2^661181397 is an apocalyptic number.

It is an amenable number.

661181397 is a deficient number, since it is larger than the sum of its proper divisors (224347947).

661181397 is a wasteful number, since it uses less digits than its factorization.

661181397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 988539.

The product of its digits is 54432, while the sum is 42.

The square root of 661181397 is about 25713.4477851571. The cubic root of 661181397 is about 871.1779512090.

The spelling of 661181397 in words is "six hundred sixty-one million, one hundred eighty-one thousand, three hundred ninety-seven".