21505084071772 has 96 divisors (see below), whose sum is σ = 45034854359040. Its totient is φ = 8791295938560.

The previous prime is 21505084071769. The next prime is 21505084071853. The reversal of 21505084071772 is 27717048050512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 98675628 + ... + 98893324.

It is an arithmetic number, because the mean of its divisors is an integer number (469113066240).

Almost surely, 2^{21505084071772} 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 21505084071772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22517427179520).

21505084071772 is an abundant number, since it is smaller than the sum of its proper divisors (23529770287268).

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

21505084071772 is a wasteful number, since it uses less digits than its factorization.

21505084071772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219371 (or 219369 counting only the distinct ones).

The product of its (nonzero) digits is 1097600, while the sum is 49.

The spelling of 21505084071772 in words is "twenty-one trillion, five hundred five billion, eighty-four million, seventy-one thousand, seven hundred seventy-two".