21116500061491 has 2 divisors, whose sum is σ = 21116500061492. Its totient is φ = 21116500061490.

The previous prime is 21116500061483. The next prime is 21116500061533. The reversal of 21116500061491 is 19416000561112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21116500061491 - 2³ = 21116500061483 is a prime.

It is a super-2 number, since 2×21116500061491² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21116500061491.

It is not a weakly prime, because it can be changed into another prime (21116500061791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10558250030745 + 10558250030746.

It is an arithmetic number, because the mean of its divisors is an integer number (10558250030746).

Almost surely, 2^{21116500061491} is an apocalyptic number.

21116500061491 is a deficient number, since it is larger than the sum of its proper divisors (1).

21116500061491 is an equidigital number, since it uses as much as digits as its factorization.

21116500061491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12960, while the sum is 37.

The spelling of 21116500061491 in words is "twenty-one trillion, one hundred sixteen billion, five hundred million, sixty-one thousand, four hundred ninety-one".