147821 has 4 divisors (see below), whose sum is σ = 154272. Its totient is φ = 141372.

The previous prime is 147811. The next prime is 147827. The reversal of 147821 is 128741.

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, and also an emirpimes, since its reverse is a distinct semiprime: 128741 = 17 ⋅7573.

It is a cyclic number.

It is not a de Polignac number, because 147821 - 2¹⁴ = 131437 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 6427 = 147821 / (1 + 4 + 7 + 8 + 2 + 1).

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 147821.

It is not an unprimeable number, because it can be changed into a prime (147827) 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, 3191 + ... + 3236.

It is an arithmetic number, because the mean of its divisors is an integer number (38568).

2¹⁴⁷⁸²¹ is an apocalyptic number.

It is an amenable number.

147821 is a deficient number, since it is larger than the sum of its proper divisors (6451).

147821 is an equidigital number, since it uses as much as digits as its factorization.

147821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6450.

The product of its digits is 448, while the sum is 23.

The square root of 147821 is about 384.4749666753. The cubic root of 147821 is about 52.8743910457.

The spelling of 147821 in words is "one hundred forty-seven thousand, eight hundred twenty-one".