21531223943 has 2 divisors, whose sum is σ = 21531223944. Its totient is φ = 21531223942.

The previous prime is 21531223921. The next prime is 21531223997. The reversal of 21531223943 is 34932213512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21531223943 - 2⁸ = 21531223687 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21531222943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765611971 + 10765611972.

It is an arithmetic number, because the mean of its divisors is an integer number (10765611972).

Almost surely, 2^21531223943 is an apocalyptic number.

21531223943 is a deficient number, since it is larger than the sum of its proper divisors (1).

21531223943 is an equidigital number, since it uses as much as digits as its factorization.

21531223943 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 35.

The spelling of 21531223943 in words is "twenty-one billion, five hundred thirty-one million, two hundred twenty-three thousand, nine hundred forty-three".