656421 has 16 divisors (see below), whose sum is σ = 946368. Its totient is φ = 403200.

The previous prime is 656407. The next prime is 656423. The reversal of 656421 is 124656.

It is not a de Polignac number, because 656421 - 2⁵ = 656389 is a prime.

656421 is an undulating number in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 656391 and 656400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656423) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3006 + ... + 3216.

It is an arithmetic number, because the mean of its divisors is an integer number (59148).

2⁶⁵⁶⁴²¹ is an apocalyptic number.

656421 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

656421 is a deficient number, since it is larger than the sum of its proper divisors (289947).

656421 is a wasteful number, since it uses less digits than its factorization.

656421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 292.

The product of its digits is 1440, while the sum is 24.

The square root of 656421 is about 810.1981239178. The cubic root of 656421 is about 86.9082134102.

The spelling of 656421 in words is "six hundred fifty-six thousand, four hundred twenty-one".