1581667 has 4 divisors (see below), whose sum is σ = 1604016. Its totient is φ = 1559320.

The previous prime is 1581653. The next prime is 1581673. The reversal of 1581667 is 7661851.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1581667 - 2⁷ = 1581539 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1581607) 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, 11068 + ... + 11209.

It is an arithmetic number, because the mean of its divisors is an integer number (401004).

2^1581667 is an apocalyptic number.

1581667 is a deficient number, since it is larger than the sum of its proper divisors (22349).

1581667 is an equidigital number, since it uses as much as digits as its factorization.

1581667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22348.

The product of its digits is 10080, while the sum is 34.

The square root of 1581667 is about 1257.6434311839. The cubic root of 1581667 is about 116.5122755950.

The spelling of 1581667 in words is "one million, five hundred eighty-one thousand, six hundred sixty-seven".