21365694870 has 96 divisors (see below), whose sum is σ = 55582060032. Its totient is φ = 5253895296.

The previous prime is 21365694851. The next prime is 21365694887. The reversal of 21365694870 is 7849656312.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7720227 + ... + 7722993.

It is an arithmetic number, because the mean of its divisors is an integer number (578979792).

It is a 1-persistent number, because it is pandigital, but 2⋅21365694870 = 42731389740 is not.

Almost surely, 2^21365694870 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21365694870, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27791030016).

21365694870 is an abundant number, since it is smaller than the sum of its proper divisors (34216365162).

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

21365694870 is a wasteful number, since it uses less digits than its factorization.

21365694870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4326 (or 4313 counting only the distinct ones).

The product of its (nonzero) digits is 2177280, while the sum is 51.

The spelling of 21365694870 in words is "twenty-one billion, three hundred sixty-five million, six hundred ninety-four thousand, eight hundred seventy".