21111242544 has 400 divisors, whose sum is σ = 72610717696. Its totient is φ = 5794675200.

The previous prime is 21111242533. The next prime is 21111242561. The reversal of 21111242544 is 44524211112.

21111242544 is a `hidden beast` number, since 2 + 1 + 1 + 112 + 4 + 2 + 544 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 76213734 + ... + 76214010.

Almost surely, 2^21111242544 is an apocalyptic number.

21111242544 is a gapful number since it is divisible by the number (24) 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 21111242544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36305358848).

21111242544 is an abundant number, since it is smaller than the sum of its proper divisors (51499475152).

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

21111242544 is a wasteful number, since it uses less digits than its factorization.

21111242544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 606 (or 591 counting only the distinct ones).

The product of its digits is 2560, while the sum is 27.

Adding to 21111242544 its reverse (44524211112), we get a palindrome (65635453656).

The spelling of 21111242544 in words is "twenty-one billion, one hundred eleven million, two hundred forty-two thousand, five hundred forty-four".