391632121 has 4 divisors (see below), whose sum is σ = 391886500. Its totient is φ = 391377744.

The previous prime is 391632103. The next prime is 391632149. The reversal of 391632121 is 121236193.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 121236193 = 13 ⋅9325861.

It can be written as a sum of positive squares in 2 ways, for example, as 77633721 + 313998400 = 8811^2 + 17720^2 .

It is a cyclic number.

It is not a de Polignac number, because 391632121 - 2¹³ = 391623929 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 391632121.

It is not an unprimeable number, because it can be changed into a prime (391632421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124866 + ... + 127963.

It is an arithmetic number, because the mean of its divisors is an integer number (97971625).

Almost surely, 2^391632121 is an apocalyptic number.

It is an amenable number.

391632121 is a deficient number, since it is larger than the sum of its proper divisors (254379).

391632121 is a wasteful number, since it uses less digits than its factorization.

391632121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 254378.

The product of its digits is 1944, while the sum is 28.

The square root of 391632121 is about 19789.6973448307. The cubic root of 391632121 is about 731.6321278786.

The spelling of 391632121 in words is "three hundred ninety-one million, six hundred thirty-two thousand, one hundred twenty-one".