21111543540 has 144 divisors (see below), whose sum is σ = 68700602880. Its totient is φ = 5435579520.

The previous prime is 21111543529. The next prime is 21111543559. The reversal of 21111543540 is 4534511112.

21111543540 is a `hidden beast` number, since 2 + 1 + 1 + 115 + 4 + 3 + 540 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 66045 + ... + 215835.

It is an arithmetic number, because the mean of its divisors is an integer number (477087520).

Almost surely, 2^21111543540 is an apocalyptic number.

21111543540 is a gapful number since it is divisible by the number (20) 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 21111543540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34350301440).

21111543540 is an abundant number, since it is smaller than the sum of its proper divisors (47589059340).

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

21111543540 is a wasteful number, since it uses less digits than its factorization.

21111543540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149844 (or 149830 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The spelling of 21111543540 in words is "twenty-one billion, one hundred eleven million, five hundred forty-three thousand, five hundred forty".