2161355724025 has 27 divisors (see below), whose sum is σ = 2775958256461. Its totient is φ = 1669296315680.

The previous prime is 2161355724013. The next prime is 2161355724049. The reversal of 2161355724025 is 5204275531612.

The square root of 2161355724025 is 1470155.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 29709003769 + 2131646720256 = 172363^2 + 1460016^2 .

It is not a de Polignac number, because 2161355724025 - 2⁷ = 2161355723897 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 213167406 + ... + 213177544.

Almost surely, 2^{2161355724025} is an apocalyptic number.

2161355724025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

2161355724025 is the 1470155-th square number.

2161355724025 is the 735078-th centered octagonal number.

It is an amenable number.

2161355724025 is a deficient number, since it is larger than the sum of its proper divisors (614602532436).

2161355724025 is an frugal number, since it uses more digits than its factorization.

2161355724025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20346 (or 10173 counting only the distinct ones).

The product of its (nonzero) digits is 504000, while the sum is 43.

The spelling of 2161355724025 in words is "two trillion, one hundred sixty-one billion, three hundred fifty-five million, seven hundred twenty-four thousand, twenty-five".