1257661 has 4 divisors (see below), whose sum is σ = 1260000. Its totient is φ = 1255324.

The previous prime is 1257653. The next prime is 1257689. The reversal of 1257661 is 1667521.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1667521 = 31 ⋅53791.

It is a cyclic number.

It is not a de Polignac number, because 1257661 - 2³ = 1257653 is a prime.

It is a super-2 number, since 2×1257661² = 3163422381842, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1257611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90 + ... + 1588.

It is an arithmetic number, because the mean of its divisors is an integer number (315000).

2^1257661 is an apocalyptic number.

It is an amenable number.

1257661 is a deficient number, since it is larger than the sum of its proper divisors (2339).

1257661 is an equidigital number, since it uses as much as digits as its factorization.

1257661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2338.

The product of its digits is 2520, while the sum is 28.

The square root of 1257661 is about 1121.4548586546. The cubic root of 1257661 is about 107.9413547634.

The spelling of 1257661 in words is "one million, two hundred fifty-seven thousand, six hundred sixty-one".