21505215143412 has 1080 divisors, whose sum is σ = 77246387640576. Its totient is φ = 5103933120000.

The previous prime is 21505215143387. The next prime is 21505215143429. The reversal of 21505215143412 is 21434151250512.

21505215143412 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 5 + 215 + 1 + 434 + 1 + 2 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 359 ways as a sum of consecutive naturals, for example, 4684209237 + ... + 4684213827.

Almost surely, 2^{21505215143412} is an apocalyptic number.

21505215143412 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21505215143412, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38623193820288).

21505215143412 is an abundant number, since it is smaller than the sum of its proper divisors (55741172497164).

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

21505215143412 is a wasteful number, since it uses less digits than its factorization.

21505215143412 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4763 (or 4728 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 36.

Adding to 21505215143412 its reverse (21434151250512), we get a palindrome (42939366393924).

The spelling of 21505215143412 in words is "twenty-one trillion, five hundred five billion, two hundred fifteen million, one hundred forty-three thousand, four hundred twelve".