1221021 has 16 divisors (see below), whose sum is σ = 1854720. Its totient is φ = 793440.

The previous prime is 1221019. The next prime is 1221029. The reversal of 1221021 is 1201221.

It is not a de Polignac number, because 1221021 - 2¹ = 1221019 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 1220994 and 1221012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221029) 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, 556 + ... + 1658.

It is an arithmetic number, because the mean of its divisors is an integer number (115920).

2^1221021 is an apocalyptic number.

It is an amenable number.

1221021 is a deficient number, since it is larger than the sum of its proper divisors (633699).

1221021 is a wasteful number, since it uses less digits than its factorization.

1221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1153 (or 1147 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 1221021 is about 1104.9981900438. The cubic root of 1221021 is about 106.8827725957.

Adding to 1221021 its reverse (1201221), we get a palindrome (2422242).

It can be divided in two parts, 12 and 21021, that multiplied together give a palindrome (252252).

The spelling of 1221021 in words is "one million, two hundred twenty-one thousand, twenty-one".