21165120024 has 32 divisors (see below), whose sum is σ = 52939656000. Its totient is φ = 7051459232.

The previous prime is 21165120001. The next prime is 21165120029. The reversal of 21165120024 is 42002156112.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a junction number, because it is equal to n+sod(n) for n = 21165119976 and 21165120003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21165120029) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 175314 + ... + 270305.

It is an arithmetic number, because the mean of its divisors is an integer number (1654364250).

Almost surely, 2^21165120024 is an apocalyptic number.

21165120024 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21165120024 is an abundant number, since it is smaller than the sum of its proper divisors (31774535976).

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

21165120024 is a wasteful number, since it uses less digits than its factorization.

21165120024 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 447607 (or 447603 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 24.

Adding to 21165120024 its reverse (42002156112), we get a palindrome (63167276136).

The spelling of 21165120024 in words is "twenty-one billion, one hundred sixty-five million, one hundred twenty thousand, twenty-four".