657421 has 4 divisors (see below), whose sum is σ = 659232. Its totient is φ = 655612.

The previous prime is 657413. The next prime is 657431. The reversal of 657421 is 124756.

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 657421 - 2³ = 657413 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 (657431) 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, 151 + ... + 1156.

It is an arithmetic number, because the mean of its divisors is an integer number (164808).

2⁶⁵⁷⁴²¹ is an apocalyptic number.

It is an amenable number.

657421 is a deficient number, since it is larger than the sum of its proper divisors (1811).

657421 is a wasteful number, since it uses less digits than its factorization.

657421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1810.

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

The square root of 657421 is about 810.8150220611. The cubic root of 657421 is about 86.9523233734.

The spelling of 657421 in words is "six hundred fifty-seven thousand, four hundred twenty-one".