21011155512 has 64 divisors (see below), whose sum is σ = 53652097920. Its totient is φ = 6855159168.

The previous prime is 21011155483. The next prime is 21011155549. The reversal of 21011155512 is 21555111012.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 210843 + ... + 294069.

It is an arithmetic number, because the mean of its divisors is an integer number (838314030).

Almost surely, 2^21011155512 is an apocalyptic number.

It is an amenable number.

21011155512 is an abundant number, since it is smaller than the sum of its proper divisors (32640942408).

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

21011155512 is a wasteful number, since it uses less digits than its factorization.

21011155512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83460 (or 83456 counting only the distinct ones).

The product of its (nonzero) digits is 500, while the sum is 24.

Adding to 21011155512 its reverse (21555111012), we get a palindrome (42566266524).

The spelling of 21011155512 in words is "twenty-one billion, eleven million, one hundred fifty-five thousand, five hundred twelve".