851621 has 8 divisors (see below), whose sum is σ = 904704. Its totient is φ = 799920.

The previous prime is 851603. The next prime is 851623. The reversal of 851621 is 126158.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-851621 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (851623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1100 + ... + 1706.

It is an arithmetic number, because the mean of its divisors is an integer number (113088).

2⁸⁵¹⁶²¹ is an apocalyptic number.

It is an amenable number.

851621 is a deficient number, since it is larger than the sum of its proper divisors (53083).

851621 is a wasteful number, since it uses less digits than its factorization.

851621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 691.

The product of its digits is 480, while the sum is 23.

The square root of 851621 is about 922.8331376798. The cubic root of 851621 is about 94.7870020219.

Adding to 851621 its reverse (126158), we get a palindrome (977779).

The spelling of 851621 in words is "eight hundred fifty-one thousand, six hundred twenty-one".