157821 has 8 divisors (see below), whose sum is σ = 217344. Its totient is φ = 101760.

The previous prime is 157813. The next prime is 157823. The reversal of 157821 is 128751.

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

It is not a de Polignac number, because 157821 - 2³ = 157813 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 157791 and 157800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (157823) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 756 + ... + 941.

It is an arithmetic number, because the mean of its divisors is an integer number (27168).

2¹⁵⁷⁸²¹ is an apocalyptic number.

It is an amenable number.

157821 is a deficient number, since it is larger than the sum of its proper divisors (59523).

157821 is a wasteful number, since it uses less digits than its factorization.

157821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1731.

The product of its digits is 560, while the sum is 24.

The square root of 157821 is about 397.2669127929. The cubic root of 157821 is about 54.0407785259.

The spelling of 157821 in words is "one hundred fifty-seven thousand, eight hundred twenty-one".