391281661 has 8 divisors (see below), whose sum is σ = 392921280. Its totient is φ = 389646528.

The previous prime is 391281643. The next prime is 391281677. The reversal of 391281661 is 166182193.

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 391281661 - 2⁵ = 391281629 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 391281661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391281691) 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, 400005 + ... + 400981.

It is an arithmetic number, because the mean of its divisors is an integer number (49115160).

Almost surely, 2^391281661 is an apocalyptic number.

It is an amenable number.

391281661 is a deficient number, since it is larger than the sum of its proper divisors (1639619).

391281661 is an equidigital number, since it uses as much as digits as its factorization.

391281661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2243.

The product of its digits is 15552, while the sum is 37.

The square root of 391281661 is about 19780.8407556403. The cubic root of 391281661 is about 731.4138240983.

The spelling of 391281661 in words is "three hundred ninety-one million, two hundred eighty-one thousand, six hundred sixty-one".