21509628543 has 64 divisors (see below), whose sum is σ = 35887380480. Its totient is φ = 12633629184.

The previous prime is 21509628523. The next prime is 21509628559. The reversal of 21509628543 is 34582690512.

21509628543 is a `hidden beast` number, since 2 + 1 + 509 + 62 + 85 + 4 + 3 = 666.

It is not a de Polignac number, because 21509628543 - 2²⁴ = 21492851327 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21509628523) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4058071 + ... + 4063367.

It is an arithmetic number, because the mean of its divisors is an integer number (560740320).

Almost surely, 2^21509628543 is an apocalyptic number.

21509628543 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21509628543 is a deficient number, since it is larger than the sum of its proper divisors (14377751937).

21509628543 is a wasteful number, since it uses less digits than its factorization.

21509628543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5845 (or 5839 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 45.

The spelling of 21509628543 in words is "twenty-one billion, five hundred nine million, six hundred twenty-eight thousand, five hundred forty-three".