21161520162425 has 18 divisors (see below), whose sum is σ = 27694040414958. Its totient is φ = 16038204747840.

The previous prime is 21161520162413. The next prime is 21161520162493. The reversal of 21161520162425 is 52426102516112.

It can be written as a sum of positive squares in 3 ways, for example, as 7279614101776 + 13881906060649 = 2698076^2 + 3725843^2 .

It is not a de Polignac number, because 21161520162425 - 2⁶ = 21161520162361 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1172374364 + ... + 1172392413.

It is an arithmetic number, because the mean of its divisors is an integer number (1538557800831).

Almost surely, 2^{21161520162425} is an apocalyptic number.

21161520162425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21161520162425 is a deficient number, since it is larger than the sum of its proper divisors (6532520252533).

21161520162425 is a wasteful number, since it uses less digits than its factorization.

21161520162425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2344766825 (or 2344766801 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 38.

Adding to 21161520162425 its reverse (52426102516112), we get a palindrome (73587622678537).

The spelling of 21161520162425 in words is "twenty-one trillion, one hundred sixty-one billion, five hundred twenty million, one hundred sixty-two thousand, four hundred twenty-five".