21611121650551 has 2 divisors, whose sum is σ = 21611121650552. Its totient is φ = 21611121650550.

The previous prime is 21611121650497. The next prime is 21611121650557. The reversal of 21611121650551 is 15505612111612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21611121650551 - 2²¹ = 21611119553399 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21611121650551.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21611121650557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10805560825275 + 10805560825276.

It is an arithmetic number, because the mean of its divisors is an integer number (10805560825276).

Almost surely, 2^{21611121650551} is an apocalyptic number.

21611121650551 is a deficient number, since it is larger than the sum of its proper divisors (1).

21611121650551 is an equidigital number, since it uses as much as digits as its factorization.

21611121650551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18000, while the sum is 37.

The spelling of 21611121650551 in words is "twenty-one trillion, six hundred eleven billion, one hundred twenty-one million, six hundred fifty thousand, five hundred fifty-one".