21070727808 has 128 divisors (see below), whose sum is σ = 60336769920. Its totient is φ = 6476599296.

The previous prime is 21070727801. The next prime is 21070727833. The reversal of 21070727808 is 80872707012.

It is a tau number, because it is divible by the number of its divisors (128).

It is a self number, because there is not a number n which added to its sum of digits gives 21070727808.

It is not an unprimeable number, because it can be changed into a prime (21070727801) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 7221966 + ... + 7224882.

It is an arithmetic number, because the mean of its divisors is an integer number (471381015).

Almost surely, 2^21070727808 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21070727808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30168384960).

21070727808 is an abundant number, since it is smaller than the sum of its proper divisors (39266042112).

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

21070727808 is a wasteful number, since it uses less digits than its factorization.

21070727808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4394 (or 4382 counting only the distinct ones).

The product of its (nonzero) digits is 87808, while the sum is 42.

The spelling of 21070727808 in words is "twenty-one billion, seventy million, seven hundred twenty-seven thousand, eight hundred eight".