1581421 has 2 divisors, whose sum is σ = 1581422. Its totient is φ = 1581420.

The previous prime is 1581413. The next prime is 1581431. The reversal of 1581421 is 1241851.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1368900 + 212521 = 1170^2 + 461^2 .

It is a cyclic number.

It is not a de Polignac number, because 1581421 - 2³ = 1581413 is a prime.

It is a nialpdrome in base 12.

It is a junction number, because it is equal to n+sod(n) for n = 1581392 and 1581401.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1581431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 790710 + 790711.

It is an arithmetic number, because the mean of its divisors is an integer number (790711).

2^1581421 is an apocalyptic number.

It is an amenable number.

1581421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1581421 is an equidigital number, since it uses as much as digits as its factorization.

1581421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 320, while the sum is 22.

The square root of 1581421 is about 1257.5456254148. The cubic root of 1581421 is about 116.5062348152.

It can be divided in two parts, 1581 and 421, that added together give a palindrome (2002).

The spelling of 1581421 in words is "one million, five hundred eighty-one thousand, four hundred twenty-one".