765421 has 4 divisors (see below), whose sum is σ = 790144. Its totient is φ = 740700.

The previous prime is 765409. The next prime is 765437. The reversal of 765421 is 124567.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 765421 - 2⁵ = 765389 is a prime.

It is a Duffinian number.

765421 is a lucky number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (765461) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12315 + ... + 12376.

It is an arithmetic number, because the mean of its divisors is an integer number (197536).

2⁷⁶⁵⁴²¹ is an apocalyptic number.

It is an amenable number.

765421 is a deficient number, since it is larger than the sum of its proper divisors (24723).

765421 is a wasteful number, since it uses less digits than its factorization.

765421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24722.

The product of its digits is 1680, while the sum is 25.

The square root of 765421 is about 874.8834208053. The cubic root of 765421 is about 91.4745168766.

Adding to 765421 its reverse (124567), we get a palindrome (889988).

The spelling of 765421 in words is "seven hundred sixty-five thousand, four hundred twenty-one".