21155055012 has 384 divisors, whose sum is σ = 71545958400. Its totient is φ = 5249359872.

The previous prime is 21155055001. The next prime is 21155055013. The reversal of 21155055012 is 21055055112.

21155055012 is a `hidden beast` number, since 2 + 1 + 155 + 0 + 5 + 501 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21155055013) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 36038983 + ... + 36039569.

It is an arithmetic number, because the mean of its divisors is an integer number (186317600).

Almost surely, 2^21155055012 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 21155055012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35772979200).

21155055012 is an abundant number, since it is smaller than the sum of its proper divisors (50390903388).

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

21155055012 is a wasteful number, since it uses less digits than its factorization.

21155055012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 832 (or 824 counting only the distinct ones).

The product of its (nonzero) digits is 2500, while the sum is 27.

The spelling of 21155055012 in words is "twenty-one billion, one hundred fifty-five million, fifty-five thousand, twelve".