1161721 has 6 divisors (see below), whose sum is σ = 1277066. Its totient is φ = 1056000.

The previous prime is 1161703. The next prime is 1161749. The reversal of 1161721 is 1271611.

It can be written as a sum of positive squares in only one way, i.e., 1092025 + 69696 = 1045^2 + 264^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1161721 is a prime.

It is a Duffinian number.

1161721 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1161761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4680 + ... + 4921.

2^1161721 is an apocalyptic number.

1161721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1161721 is a deficient number, since it is larger than the sum of its proper divisors (115345).

1161721 is an equidigital number, since it uses as much as digits as its factorization.

1161721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9623 (or 9612 counting only the distinct ones).

The product of its digits is 84, while the sum is 19.

The square root of 1161721 is about 1077.8316195028. The cubic root of 1161721 is about 105.1236939847.

The spelling of 1161721 in words is "one million, one hundred sixty-one thousand, seven hundred twenty-one".