21165326221704 has 384 divisors, whose sum is σ = 66540594044160. Its totient is φ = 5572526948352.

The previous prime is 21165326221657. The next prime is 21165326221771. The reversal of 21165326221704 is 40712262356112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 515993004 + ... + 516034020.

It is an arithmetic number, because the mean of its divisors is an integer number (173282796990).

Almost surely, 2^{21165326221704} is an apocalyptic number.

21165326221704 is a gapful number since it is divisible by the number (24) 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 21165326221704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33270297022080).

21165326221704 is an abundant number, since it is smaller than the sum of its proper divisors (45375267822456).

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

21165326221704 is a wasteful number, since it uses less digits than its factorization.

21165326221704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41597 (or 41586 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 42.

Adding to 21165326221704 its reverse (40712262356112), we get a palindrome (61877588577816).

The spelling of 21165326221704 in words is "twenty-one trillion, one hundred sixty-five billion, three hundred twenty-six million, two hundred twenty-one thousand, seven hundred four".