21121751087 has 2 divisors, whose sum is σ = 21121751088. Its totient is φ = 21121751086.

The previous prime is 21121751083. The next prime is 21121751089. The reversal of 21121751087 is 78015712112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21121751087 - 2² = 21121751083 is a prime.

It is a super-2 number, since 2×21121751087² (a number of 21 digits) contains 22 as substring.

Together with 21121751089, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21121751081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560875543 + 10560875544.

It is an arithmetic number, because the mean of its divisors is an integer number (10560875544).

Almost surely, 2^21121751087 is an apocalyptic number.

21121751087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121751087 is an equidigital number, since it uses as much as digits as its factorization.

21121751087 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7840, while the sum is 35.

The spelling of 21121751087 in words is "twenty-one billion, one hundred twenty-one million, seven hundred fifty-one thousand, eighty-seven".