20990143 has 2 divisors, whose sum is σ = 20990144. Its totient is φ = 20990142.

The previous prime is 20990111. The next prime is 20990183. The reversal of 20990143 is 34109902.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20990143 - 2⁵ = 20990111 is a prime.

It is a super-2 number, since 2×20990143² = 881172206320898, which contains 22 as substring.

It is the 4582-nd Hogben number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20990183) by changing a digit.

It is a nontrivial repunit in base 4581.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10495071 + 10495072.

It is an arithmetic number, because the mean of its divisors is an integer number (10495072).

Almost surely, 2^20990143 is an apocalyptic number.

20990143 is a deficient number, since it is larger than the sum of its proper divisors (1).

20990143 is an equidigital number, since it uses as much as digits as its factorization.

20990143 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 20990143 is about 4581.5000818509. The cubic root of 20990143 is about 275.8492446673.

The spelling of 20990143 in words is "twenty million, nine hundred ninety thousand, one hundred forty-three".