1921221 has 24 divisors (see below), whose sum is σ = 3046680. Its totient is φ = 1161216.

The previous prime is 1921211. The next prime is 1921229. The reversal of 1921221 is 1221291.

It can be written as a sum of positive squares in 4 ways, for example, as 202500 + 1718721 = 450^2 + 1311^2 .

It is not a de Polignac number, because 1921221 - 2¹⁷ = 1790149 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1921194 and 1921203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1921229) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4221 + ... + 4653.

It is an arithmetic number, because the mean of its divisors is an integer number (126945).

2^1921221 is an apocalyptic number.

It is an amenable number.

1921221 is a deficient number, since it is larger than the sum of its proper divisors (1125459).

1921221 is a wasteful number, since it uses less digits than its factorization.

1921221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 485 (or 482 counting only the distinct ones).

The product of its digits is 72, while the sum is 18.

The square root of 1921221 is about 1386.0811664545. The cubic root of 1921221 is about 124.3156413975.

It can be divided in two parts, 192 and 1221, that multiplied together give a palindrome (234432).

The spelling of 1921221 in words is "one million, nine hundred twenty-one thousand, two hundred twenty-one".