216961301591 has 4 divisors (see below), whose sum is σ = 216962300352. Its totient is φ = 216960302832.

The previous prime is 216961301581. The next prime is 216961301611. The reversal of 216961301591 is 195103169612.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 216961301591 - 2¹⁸ = 216961039447 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216961301561) 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, 20390 + ... + 659043.

It is an arithmetic number, because the mean of its divisors is an integer number (54240575088).

Almost surely, 2^216961301591 is an apocalyptic number.

216961301591 is a deficient number, since it is larger than the sum of its proper divisors (998761).

216961301591 is an equidigital number, since it uses as much as digits as its factorization.

216961301591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 998760.

The product of its (nonzero) digits is 87480, while the sum is 44.

The spelling of 216961301591 in words is "two hundred sixteen billion, nine hundred sixty-one million, three hundred one thousand, five hundred ninety-one".