21130781952 has 216 divisors, whose sum is σ = 65611713216. Its totient is φ = 6019743744.

The previous prime is 21130781899. The next prime is 21130781957. The reversal of 21130781952 is 25918703112.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21130781952.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21130781957) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18326208 + ... + 18327360.

Almost surely, 2^21130781952 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 21130781952, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32805856608).

21130781952 is an abundant number, since it is smaller than the sum of its proper divisors (44480931264).

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

21130781952 is a wasteful number, since it uses less digits than its factorization.

21130781952 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1673 (or 1652 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 39.

The spelling of 21130781952 in words is "twenty-one billion, one hundred thirty million, seven hundred eighty-one thousand, nine hundred fifty-two".