165731421 has 8 divisors (see below), whose sum is σ = 221193280. Its totient is φ = 110378592.

The previous prime is 165731411. The next prime is 165731437. The reversal of 165731421 is 124137561.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 165731421 - 2¹⁸ = 165469277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165731411) 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, 23641 + ... + 29838.

It is an arithmetic number, because the mean of its divisors is an integer number (27649160).

Almost surely, 2^165731421 is an apocalyptic number.

It is an amenable number.

165731421 is a deficient number, since it is larger than the sum of its proper divisors (55461859).

165731421 is a wasteful number, since it uses less digits than its factorization.

165731421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54515.

The product of its digits is 5040, while the sum is 30.

The square root of 165731421 is about 12873.6716207926. The cubic root of 165731421 is about 549.2899056440.

Adding to 165731421 its reverse (124137561), we get a palindrome (289868982).

The spelling of 165731421 in words is "one hundred sixty-five million, seven hundred thirty-one thousand, four hundred twenty-one".