1261661 has 4 divisors (see below), whose sum is σ = 1271424. Its totient is φ = 1251900.

The previous prime is 1261649. The next prime is 1261697. The reversal of 1261661 is 1661621.

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: 1661621 = 13 ⋅127817.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1261661 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261261) 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, 4685 + ... + 4946.

It is an arithmetic number, because the mean of its divisors is an integer number (317856).

2^1261661 is an apocalyptic number.

It is an amenable number.

1261661 is a deficient number, since it is larger than the sum of its proper divisors (9763).

1261661 is an equidigital number, since it uses as much as digits as its factorization.

1261661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9762.

The product of its digits is 432, while the sum is 23.

The square root of 1261661 is about 1123.2368405639. The cubic root of 1261661 is about 108.0556697449.

The spelling of 1261661 in words is "one million, two hundred sixty-one thousand, six hundred sixty-one".