21111210997951 has 2 divisors, whose sum is σ = 21111210997952. Its totient is φ = 21111210997950.

The previous prime is 21111210997939. The next prime is 21111210997991. The reversal of 21111210997951 is 15979901211112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111210997951 is a prime.

It is a super-3 number, since 3×21111210997951³ (a number of 41 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21111210997895 and 21111210997904.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111210997931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555605498975 + 10555605498976.

It is an arithmetic number, because the mean of its divisors is an integer number (10555605498976).

Almost surely, 2^{21111210997951} is an apocalyptic number.

21111210997951 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111210997951 is an equidigital number, since it uses as much as digits as its factorization.

21111210997951 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 102060, while the sum is 49.

The spelling of 21111210997951 in words is "twenty-one trillion, one hundred eleven billion, two hundred ten million, nine hundred ninety-seven thousand, nine hundred fifty-one".