21030137856 has 312 divisors, whose sum is σ = 74776621920. Its totient is φ = 5545525248.

The previous prime is 21030137851. The next prime is 21030137857. The reversal of 21030137856 is 65873103012.

It is a tau number, because it is divible by the number of its divisors (312).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21030137856.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21030137851) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3351490 + ... + 3357758.

It is an arithmetic number, because the mean of its divisors is an integer number (239668660).

Almost surely, 2^21030137856 is an apocalyptic number.

21030137856 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21030137856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37388310960).

21030137856 is an abundant number, since it is smaller than the sum of its proper divisors (53746484064).

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

21030137856 is a wasteful number, since it uses less digits than its factorization.

21030137856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6319 (or 6294 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 36.

The spelling of 21030137856 in words is "twenty-one billion, thirty million, one hundred thirty-seven thousand, eight hundred fifty-six".