1157821 has 6 divisors (see below), whose sum is σ = 1346910. Its totient is φ = 992376.

The previous prime is 1157791. The next prime is 1157831. The reversal of 1157821 is 1287511.

It can be written as a sum of positive squares in only one way, i.e., 648025 + 509796 = 805^2 + 714^2 .

It is not a de Polignac number, because 1157821 - 2¹⁵ = 1125053 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1157831) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11766 + ... + 11863.

It is an arithmetic number, because the mean of its divisors is an integer number (224485).

2^1157821 is an apocalyptic number.

It is an amenable number.

1157821 is a deficient number, since it is larger than the sum of its proper divisors (189089).

1157821 is an equidigital number, since it uses as much as digits as its factorization.

1157821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23643 (or 23636 counting only the distinct ones).

The product of its digits is 560, while the sum is 25.

The square root of 1157821 is about 1076.0209105775. The cubic root of 1157821 is about 105.0059255915.

The spelling of 1157821 in words is "one million, one hundred fifty-seven thousand, eight hundred twenty-one".