1155721 has 4 divisors (see below), whose sum is σ = 1320832. Its totient is φ = 990612.

The previous prime is 1155709. The next prime is 1155733. The reversal of 1155721 is 1275511.

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: 1275511 = 23 ⋅55457.

It is an interprime number because it is at equal distance from previous prime (1155709) and next prime (1155733).

It is not a de Polignac number, because 1155721 - 2⁵ = 1155689 is a prime.

It is a Duffinian number.

1155721 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1155692 and 1155701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1155701) 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, 82545 + ... + 82558.

It is an arithmetic number, because the mean of its divisors is an integer number (330208).

2^1155721 is an apocalyptic number.

It is an amenable number.

1155721 is a deficient number, since it is larger than the sum of its proper divisors (165111).

1155721 is an equidigital number, since it uses as much as digits as its factorization.

1155721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165110.

The product of its digits is 350, while the sum is 22.

The square root of 1155721 is about 1075.0446502355. The cubic root of 1155721 is about 104.9424022730.

The spelling of 1155721 in words is "one million, one hundred fifty-five thousand, seven hundred twenty-one".