21660973542 has 192 divisors, whose sum is σ = 53771268096. Its totient is φ = 6255325440.

The previous prime is 21660973513. The next prime is 21660973549. The reversal of 21660973542 is 24537906612.

21660973542 is a `hidden beast` number, since 2 + 1 + 6 + 609 + 7 + 35 + 4 + 2 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660973549) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 39599313 + ... + 39599859.

It is an arithmetic number, because the mean of its divisors is an integer number (280058688).

Almost surely, 2^21660973542 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21660973542, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26885634048).

21660973542 is an abundant number, since it is smaller than the sum of its proper divisors (32110294554).

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

21660973542 is a wasteful number, since it uses less digits than its factorization.

21660973542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 755 (or 752 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 45.

The spelling of 21660973542 in words is "twenty-one billion, six hundred sixty million, nine hundred seventy-three thousand, five hundred forty-two".