21545599026 has 64 divisors (see below), whose sum is σ = 52233818112. Its totient is φ = 5783791872.

The previous prime is 21545598989. The next prime is 21545599027. The reversal of 21545599026 is 62099554512.

It is not an unprimeable number, because it can be changed into a prime (21545599027) 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 31 ways as a sum of consecutive naturals, for example, 393415 + ... + 444821.

It is an arithmetic number, because the mean of its divisors is an integer number (816153408).

Almost surely, 2^21545599026 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21545599026, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26116909056).

21545599026 is an abundant number, since it is smaller than the sum of its proper divisors (30688219086).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21545599026 is a wasteful number, since it uses less digits than its factorization.

21545599026 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52023.

The product of its (nonzero) digits is 972000, while the sum is 48.

The spelling of 21545599026 in words is "twenty-one billion, five hundred forty-five million, five hundred ninety-nine thousand, twenty-six".