21506028860 has 24 divisors (see below), whose sum is σ = 45166254000. Its totient is φ = 8601727104.

The previous prime is 21506028847. The next prime is 21506028889. The reversal of 21506028860 is 6882060512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 271016 + ... + 341264.

It is an arithmetic number, because the mean of its divisors is an integer number (1881927250).

Almost surely, 2^21506028860 is an apocalyptic number.

21506028860 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21506028860 is an abundant number, since it is smaller than the sum of its proper divisors (23660225140).

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

21506028860 is a wasteful number, since it uses less digits than its factorization.

21506028860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85565 (or 85563 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 38.

The spelling of 21506028860 in words is "twenty-one billion, five hundred six million, twenty-eight thousand, eight hundred sixty".