1021121999 has 4 divisors (see below), whose sum is σ = 1024048200. Its totient is φ = 1018195800.

The previous prime is 1021121993. The next prime is 1021122013. The reversal of 1021121999 is 9991211201.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9991211201 = 23 ⋅434400487.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1021121999 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021121993) 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 in 3 ways as a sum of consecutive naturals, for example, 1462577 + ... + 1463274.

It is an arithmetic number, because the mean of its divisors is an integer number (256012050).

Almost surely, 2^1021121999 is an apocalyptic number.

1021121999 is a deficient number, since it is larger than the sum of its proper divisors (2926201).

1021121999 is an equidigital number, since it uses as much as digits as its factorization.

1021121999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2926200.

The product of its (nonzero) digits is 2916, while the sum is 35.

The square root of 1021121999 is about 31954.9995931779. Note that the first 3 decimals coincide. The cubic root of 1021121999 is about 1006.9916689727.

The spelling of 1021121999 in words is "one billion, twenty-one million, one hundred twenty-one thousand, nine hundred ninety-nine".