1165821421 has 4 divisors (see below), whose sum is σ = 1167259744. Its totient is φ = 1164383100.

The previous prime is 1165821409. The next prime is 1165821439. The reversal of 1165821421 is 1241285611.

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.

It is a cyclic number.

It is not a de Polignac number, because 1165821421 - 2¹⁷ = 1165690349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1165821821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 717945 + ... + 719566.

It is an arithmetic number, because the mean of its divisors is an integer number (291814936).

Almost surely, 2^1165821421 is an apocalyptic number.

It is an amenable number.

1165821421 is a deficient number, since it is larger than the sum of its proper divisors (1438323).

1165821421 is an equidigital number, since it uses as much as digits as its factorization.

1165821421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1438322.

The product of its digits is 3840, while the sum is 31.

The square root of 1165821421 is about 34144.1271816985. The cubic root of 1165821421 is about 1052.4723060175.

The spelling of 1165821421 in words is "one billion, one hundred sixty-five million, eight hundred twenty-one thousand, four hundred twenty-one".