21236543506 has 16 divisors (see below), whose sum is σ = 32115317760. Its totient is φ = 10531488240.

The previous prime is 21236543491. The next prime is 21236543533. The reversal of 21236543506 is 60534563212.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 987840 + ... + 1009108.

It is an arithmetic number, because the mean of its divisors is an integer number (2007207360).

Almost surely, 2^21236543506 is an apocalyptic number.

21236543506 is a deficient number, since it is larger than the sum of its proper divisors (10878774254).

21236543506 is a wasteful number, since it uses less digits than its factorization.

21236543506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25329.

The product of its (nonzero) digits is 129600, while the sum is 37.

The spelling of 21236543506 in words is "twenty-one billion, two hundred thirty-six million, five hundred forty-three thousand, five hundred six".