311661721005 has 16 divisors (see below), whose sum is σ = 499208564544. Its totient is φ = 166036314240.

The previous prime is 311661720983. The next prime is 311661721061. The reversal of 311661721005 is 500127166113.

It is not a de Polignac number, because 311661721005 - 2¹⁰ = 311661719981 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 11440336 + ... + 11467545.

It is an arithmetic number, because the mean of its divisors is an integer number (31200535284).

Almost surely, 2^311661721005 is an apocalyptic number.

It is an amenable number.

311661721005 is a deficient number, since it is larger than the sum of its proper divisors (187546843539).

311661721005 is a wasteful number, since it uses less digits than its factorization.

311661721005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22908796.

The product of its (nonzero) digits is 7560, while the sum is 33.

Adding to 311661721005 its reverse (500127166113), we get a palindrome (811788887118).

The spelling of 311661721005 in words is "three hundred eleven billion, six hundred sixty-one million, seven hundred twenty-one thousand, five".