1551221 has 4 divisors (see below), whose sum is σ = 1772832. Its totient is φ = 1329612.

The previous prime is 1551203. The next prime is 1551229. The reversal of 1551221 is 1221551.

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.

It is a cyclic number.

It is not a de Polignac number, because 1551221 - 2⁶ = 1551157 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1551221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1551229) 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, 110795 + ... + 110808.

It is an arithmetic number, because the mean of its divisors is an integer number (443208).

2^1551221 is an apocalyptic number.

It is an amenable number.

1551221 is a deficient number, since it is larger than the sum of its proper divisors (221611).

1551221 is an equidigital number, since it uses as much as digits as its factorization.

1551221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221610.

The product of its digits is 100, while the sum is 17.

The square root of 1551221 is about 1245.4802286668. The cubic root of 1551221 is about 115.7598330648.

Adding to 1551221 its reverse (1221551), we get a palindrome (2772772).

The spelling of 1551221 in words is "one million, five hundred fifty-one thousand, two hundred twenty-one".