151821 has 8 divisors (see below), whose sum is σ = 224960. Its totient is φ = 101196.

The previous prime is 151817. The next prime is 151841. The reversal of 151821 is 128151.

It is not a de Polignac number, because 151821 - 2² = 151817 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 151794 and 151803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (151841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2785 + ... + 2838.

It is an arithmetic number, because the mean of its divisors is an integer number (28120).

2¹⁵¹⁸²¹ is an apocalyptic number.

It is an amenable number.

151821 is a deficient number, since it is larger than the sum of its proper divisors (73139).

151821 is an equidigital number, since it uses as much as digits as its factorization.

151821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5632 (or 5626 counting only the distinct ones).

The product of its digits is 80, while the sum is 18.

The square root of 151821 is about 389.6421435112. The cubic root of 151821 is about 53.3470754519.

Adding to 151821 its reverse (128151), we get a palindrome (279972).

It can be divided in two parts, 1518 and 21, that multiplied together give a triangular number (31878 = T₂₅₂).

The spelling of 151821 in words is "one hundred fifty-one thousand, eight hundred twenty-one".