21234543456 has 192 divisors, whose sum is σ = 65490163200. Its totient is φ = 5898203136.

The previous prime is 21234543397. The next prime is 21234543457. The reversal of 21234543456 is 65434543212.

21234543456 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21234543457) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6615580 + ... + 6618788.

It is an arithmetic number, because the mean of its divisors is an integer number (341094600).

Almost surely, 2^21234543456 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 21234543456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32745081600).

21234543456 is an abundant number, since it is smaller than the sum of its proper divisors (44255619744).

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

21234543456 is a wasteful number, since it uses less digits than its factorization.

21234543456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3501 (or 3493 counting only the distinct ones).

The product of its digits is 345600, while the sum is 39.

The spelling of 21234543456 in words is "twenty-one billion, two hundred thirty-four million, five hundred forty-three thousand, four hundred fifty-six".