21543731507 has 2 divisors, whose sum is σ = 21543731508. Its totient is φ = 21543731506.

The previous prime is 21543731479. The next prime is 21543731519. The reversal of 21543731507 is 70513734512.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21543731507 is a prime.

It is not a weakly prime, because it can be changed into another prime (21543731597) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771865753 + 10771865754.

It is an arithmetic number, because the mean of its divisors is an integer number (10771865754).

Almost surely, 2^21543731507 is an apocalyptic number.

21543731507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21543731507 is an equidigital number, since it uses as much as digits as its factorization.

21543731507 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 88200, while the sum is 38.

The spelling of 21543731507 in words is "twenty-one billion, five hundred forty-three million, seven hundred thirty-one thousand, five hundred seven".