21121111109951 has 2 divisors, whose sum is σ = 21121111109952. Its totient is φ = 21121111109950.

The previous prime is 21121111109929. The next prime is 21121111110103. The reversal of 21121111109951 is 15990111112112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21121111109951 - 2¹⁴ = 21121111093567 is a prime.

It is a super-2 number, since 2×21121111109951² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21121111109051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560555554975 + 10560555554976.

It is an arithmetic number, because the mean of its divisors is an integer number (10560555554976).

Almost surely, 2^{21121111109951} is an apocalyptic number.

21121111109951 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121111109951 is an equidigital number, since it uses as much as digits as its factorization.

21121111109951 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1620, while the sum is 35.

The spelling of 21121111109951 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred eleven million, one hundred nine thousand, nine hundred fifty-one".