1661567 has 2 divisors, whose sum is σ = 1661568. Its totient is φ = 1661566.

The previous prime is 1661557. The next prime is 1661587. The reversal of 1661567 is 7651661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1661567 - 2⁶ = 1661503 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1661557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830783 + 830784.

It is an arithmetic number, because the mean of its divisors is an integer number (830784).

2^1661567 is an apocalyptic number.

1661567 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661567 is an equidigital number, since it uses as much as digits as its factorization.

1661567 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 32.

The square root of 1661567 is about 1289.0178431659. The cubic root of 1661567 is about 118.4420601345.

The spelling of 1661567 in words is "one million, six hundred sixty-one thousand, five hundred sixty-seven".