851421 has 4 divisors (see below), whose sum is σ = 1135232. Its totient is φ = 567612.

The previous prime is 851419. The next prime is 851423. The reversal of 851421 is 124158.

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 an interprime number because it is at equal distance from previous prime (851419) and next prime (851423).

It is not a de Polignac number, because 851421 - 2¹ = 851419 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 851421.

It is not an unprimeable number, because it can be changed into a prime (851423) 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, 141901 + ... + 141906.

It is an arithmetic number, because the mean of its divisors is an integer number (283808).

2⁸⁵¹⁴²¹ is an apocalyptic number.

It is an amenable number.

851421 is a deficient number, since it is larger than the sum of its proper divisors (283811).

851421 is a wasteful number, since it uses less digits than its factorization.

851421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283810.

The product of its digits is 320, while the sum is 21.

The square root of 851421 is about 922.7247693652. The cubic root of 851421 is about 94.7795813169.

Adding to 851421 its reverse (124158), we get a palindrome (975579).

The spelling of 851421 in words is "eight hundred fifty-one thousand, four hundred twenty-one".