21311946017218 has 4 divisors (see below), whose sum is σ = 31967919025830. Its totient is φ = 10655973008608.

The previous prime is 21311946017177. The next prime is 21311946017249. The reversal of 21311946017218 is 81271064911312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 12511663575489 + 8800282441729 = 3537183^2 + 2966527^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5327986504303 + ... + 5327986504306.

Almost surely, 2^{21311946017218} is an apocalyptic number.

21311946017218 is a deficient number, since it is larger than the sum of its proper divisors (10655973008612).

21311946017218 is a wasteful number, since it uses less digits than its factorization.

21311946017218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10655973008611.

The product of its (nonzero) digits is 145152, while the sum is 46.

The spelling of 21311946017218 in words is "twenty-one trillion, three hundred eleven billion, nine hundred forty-six million, seventeen thousand, two hundred eighteen".