165621025 has 24 divisors (see below), whose sum is σ = 210522240. Its totient is φ = 129205440.

The previous prime is 165621023. The next prime is 165621041. The reversal of 165621025 is 520126561.

It is not a de Polignac number, because 165621025 - 2¹ = 165621023 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 165620984 and 165621002.

It is not an unprimeable number, because it can be changed into a prime (165621023) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 316414 + ... + 316936.

It is an arithmetic number, because the mean of its divisors is an integer number (8771760).

Almost surely, 2^165621025 is an apocalyptic number.

It is an amenable number.

165621025 is a deficient number, since it is larger than the sum of its proper divisors (44901215).

165621025 is a wasteful number, since it uses less digits than its factorization.

165621025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 825 (or 820 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 165621025 is about 12869.3832408550. The cubic root of 165621025 is about 549.1679153433.

Adding to 165621025 its reverse (520126561), we get a palindrome (685747586).

The spelling of 165621025 in words is "one hundred sixty-five million, six hundred twenty-one thousand, twenty-five".