999121751 has 2 divisors, whose sum is σ = 999121752. Its totient is φ = 999121750.

The previous prime is 999121729. The next prime is 999121763. The reversal of 999121751 is 157121999.

It is a strong prime.

It is an emirp because it is prime and its reverse (157121999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999121751 - 2⁶ = 999121687 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999121951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499560875 + 499560876.

It is an arithmetic number, because the mean of its divisors is an integer number (499560876).

Almost surely, 2^999121751 is an apocalyptic number.

999121751 is a deficient number, since it is larger than the sum of its proper divisors (1).

999121751 is an equidigital number, since it uses as much as digits as its factorization.

999121751 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51030, while the sum is 44.

The square root of 999121751 is about 31608.8872154652. The cubic root of 999121751 is about 999.7071645891.

The spelling of 999121751 in words is "nine hundred ninety-nine million, one hundred twenty-one thousand, seven hundred fifty-one".