1231821 has 16 divisors (see below), whose sum is σ = 1869120. Its totient is φ = 801360.

The previous prime is 1231817. The next prime is 1231829. The reversal of 1231821 is 1281321.

It is not a de Polignac number, because 1231821 - 2² = 1231817 is a prime.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 1231794 and 1231803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 631 + ... + 1691.

It is an arithmetic number, because the mean of its divisors is an integer number (116820).

2^1231821 is an apocalyptic number.

It is an amenable number.

1231821 is a deficient number, since it is larger than the sum of its proper divisors (637299).

1231821 is a wasteful number, since it uses less digits than its factorization.

1231821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1113 (or 1107 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 1231821 is about 1109.8743172089. The cubic root of 1231821 is about 107.1969760879.

The spelling of 1231821 in words is "one million, two hundred thirty-one thousand, eight hundred twenty-one".