21020131999 has 2 divisors, whose sum is σ = 21020132000. Its totient is φ = 21020131998.

The previous prime is 21020131991. The next prime is 21020132017. The reversal of 21020131999 is 99913102012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21020131999 - 2³ = 21020131991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21020131991) 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, 10510065999 + 10510066000.

It is an arithmetic number, because the mean of its divisors is an integer number (10510066000).

Almost surely, 2^21020131999 is an apocalyptic number.

21020131999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020131999 is an equidigital number, since it uses as much as digits as its factorization.

21020131999 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8748, while the sum is 37.

It can be divided in two parts, 2102013 and 1999, that added together give a palindrome (2104012).

The spelling of 21020131999 in words is "twenty-one billion, twenty million, one hundred thirty-one thousand, nine hundred ninety-nine".