20111999 has 2 divisors, whose sum is σ = 20112000. Its totient is φ = 20111998.

The previous prime is 20111981. The next prime is 20112007. The reversal of 20111999 is 99911102.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20111999 - 2²⁰ = 19063423 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20113999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10055999 + 10056000.

It is an arithmetic number, because the mean of its divisors is an integer number (10056000).

Almost surely, 2^20111999 is an apocalyptic number.

20111999 is a deficient number, since it is larger than the sum of its proper divisors (1).

20111999 is an equidigital number, since it uses as much as digits as its factorization.

20111999 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1458, while the sum is 32.

The square root of 20111999 is about 4484.6403423240. The cubic root of 20111999 is about 271.9475055486.

The spelling of 20111999 in words is "twenty million, one hundred eleven thousand, nine hundred ninety-nine".