21543731501 has 4 divisors (see below), whose sum is σ = 21549215904. Its totient is φ = 21538247100.

The previous prime is 21543731479. The next prime is 21543731507. The reversal of 21543731501 is 10513734512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21543731501 - 2⁶ = 21543731437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21543731507) 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 in 3 ways as a sum of consecutive naturals, for example, 2736305 + ... + 2744166.

It is an arithmetic number, because the mean of its divisors is an integer number (5387303976).

Almost surely, 2^21543731501 is an apocalyptic number.

It is an amenable number.

21543731501 is a deficient number, since it is larger than the sum of its proper divisors (5484403).

21543731501 is an equidigital number, since it uses as much as digits as its factorization.

21543731501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5484402.

The product of its (nonzero) digits is 12600, while the sum is 32.

The spelling of 21543731501 in words is "twenty-one billion, five hundred forty-three million, seven hundred thirty-one thousand, five hundred one".