1557421 has 8 divisors (see below), whose sum is σ = 1659960. Its totient is φ = 1461184.

The previous prime is 1557419. The next prime is 1557427. The reversal of 1557421 is 1247551.

It can be written as a sum of positive squares in 4 ways, for example, as 44521 + 1512900 = 211^2 + 1230^2 .

It is not a de Polignac number, because 1557421 - 2¹ = 1557419 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1557427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4755 + ... + 5071.

It is an arithmetic number, because the mean of its divisors is an integer number (207495).

2^1557421 is an apocalyptic number.

It is an amenable number.

1557421 is a deficient number, since it is larger than the sum of its proper divisors (102539).

1557421 is an frugal number, since it uses more digits than its factorization.

1557421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 368 (or 334 counting only the distinct ones).

The product of its digits is 1400, while the sum is 25.

The square root of 1557421 is about 1247.9667463518. The cubic root of 1557421 is about 115.9138530030.

The spelling of 1557421 in words is "one million, five hundred fifty-seven thousand, four hundred twenty-one".