1657661 has 2 divisors, whose sum is σ = 1657662. Its totient is φ = 1657660.

The previous prime is 1657651. The next prime is 1657673. The reversal of 1657661 is 1667561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 902500 + 755161 = 950^2 + 869^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1657661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1657631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 828830 + 828831.

It is an arithmetic number, because the mean of its divisors is an integer number (828831).

2^1657661 is an apocalyptic number.

It is an amenable number.

1657661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1657661 is an equidigital number, since it uses as much as digits as its factorization.

1657661 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 1657661 is about 1287.5018446589. The cubic root of 1657661 is about 118.3491763927.

The spelling of 1657661 in words is "one million, six hundred fifty-seven thousand, six hundred sixty-one".