21012413056 has 64 divisors (see below), whose sum is σ = 43417532160. Its totient is φ = 10118707200.

The previous prime is 21012413053. The next prime is 21012413057. The reversal of 21012413056 is 65031421012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (64).

It is a self number, because there is not a number n which added to its sum of digits gives 21012413056.

It is not an unprimeable number, because it can be changed into a prime (21012413053) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 824700 + ... + 849796.

It is an arithmetic number, because the mean of its divisors is an integer number (678398940).

Almost surely, 2^21012413056 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 21012413056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21708766080).

21012413056 is an abundant number, since it is smaller than the sum of its proper divisors (22405119104).

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

21012413056 is a wasteful number, since it uses less digits than its factorization.

21012413056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25353 (or 25341 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

Adding to 21012413056 its reverse (65031421012), we get a palindrome (86043834068).

The spelling of 21012413056 in words is "twenty-one billion, twelve million, four hundred thirteen thousand, fifty-six".