21001532543 has 8 divisors (see below), whose sum is σ = 21699169056. Its totient is φ = 20315058400.

The previous prime is 21001532537. The next prime is 21001532549. The reversal of 21001532543 is 34523510012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21001532537) and next prime (21001532549).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21001532543 - 2⁶ = 21001532479 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 (21001532549) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2786768 + ... + 2794293.

It is an arithmetic number, because the mean of its divisors is an integer number (2712396132).

Almost surely, 2^21001532543 is an apocalyptic number.

21001532543 is a deficient number, since it is larger than the sum of its proper divisors (697636513).

21001532543 is an equidigital number, since it uses as much as digits as its factorization.

21001532543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5581185.

The product of its (nonzero) digits is 3600, while the sum is 26.

The spelling of 21001532543 in words is "twenty-one billion, one million, five hundred thirty-two thousand, five hundred forty-three".