190821 has 4 divisors (see below), whose sum is σ = 254432. Its totient is φ = 127212.

The previous prime is 190811. The next prime is 190823. The reversal of 190821 is 128091.

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: 128091 = 3 ⋅42697.

It is not a de Polignac number, because 190821 - 2¹⁰ = 189797 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (190823) 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, 31801 + ... + 31806.

It is an arithmetic number, because the mean of its divisors is an integer number (63608).

2¹⁹⁰⁸²¹ is an apocalyptic number.

It is an amenable number.

190821 is a deficient number, since it is larger than the sum of its proper divisors (63611).

190821 is an equidigital number, since it uses as much as digits as its factorization.

190821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63610.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 190821 is about 436.8306307941. The cubic root of 190821 is about 57.5716560972.

The spelling of 190821 in words is "one hundred ninety thousand, eight hundred twenty-one".