1221100043 has 4 divisors (see below), whose sum is σ = 1230013320. Its totient is φ = 1212186768.

The previous prime is 1221100033. The next prime is 1221100063. The reversal of 1221100043 is 3400011221.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1221100043 - 2¹⁸ = 1220837899 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221100033) 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, 4456433 + ... + 4456706.

It is an arithmetic number, because the mean of its divisors is an integer number (307503330).

Almost surely, 2^1221100043 is an apocalyptic number.

1221100043 is a deficient number, since it is larger than the sum of its proper divisors (8913277).

1221100043 is an equidigital number, since it uses as much as digits as its factorization.

1221100043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8913276.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 1221100043 is about 34944.2419147991. The cubic root of 1221100043 is about 1068.8507890402.

Adding to 1221100043 its reverse (3400011221), we get a palindrome (4621111264).

The spelling of 1221100043 in words is "one billion, two hundred twenty-one million, one hundred thousand, forty-three".