21161765052 has 192 divisors, whose sum is σ = 59703168000. Its totient is φ = 6459243264.

The previous prime is 21161764963. The next prime is 21161765057. The reversal of 21161765052 is 25056716112.

21161765052 is a `hidden beast` number, since 21 + 1 + 61 + 76 + 505 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21161764998 and 21161765016.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161765057) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 12678474 + ... + 12680142.

It is an arithmetic number, because the mean of its divisors is an integer number (310954000).

Almost surely, 2^21161765052 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 21161765052, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29851584000).

21161765052 is an abundant number, since it is smaller than the sum of its proper divisors (38541402948).

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

21161765052 is a wasteful number, since it uses less digits than its factorization.

21161765052 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1905 (or 1897 counting only the distinct ones).

The product of its (nonzero) digits is 25200, while the sum is 36.

The spelling of 21161765052 in words is "twenty-one billion, one hundred sixty-one million, seven hundred sixty-five thousand, fifty-two".