1221605143 has 8 divisors (see below), whose sum is σ = 1334420496. Its totient is φ = 1109083200.

The previous prime is 1221605137. The next prime is 1221605149. The reversal of 1221605143 is 3415061221.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1221605137) and next prime (1221605149).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221605143 - 2⁵ = 1221605111 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 (1221605149) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64596 + ... + 81337.

It is an arithmetic number, because the mean of its divisors is an integer number (166802562).

Almost surely, 2^1221605143 is an apocalyptic number.

1221605143 is a deficient number, since it is larger than the sum of its proper divisors (112815353).

1221605143 is a wasteful number, since it uses less digits than its factorization.

1221605143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146705.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 1221605143 is about 34951.4683954766. The cubic root of 1221605143 is about 1068.9981430906.

Adding to 1221605143 its reverse (3415061221), we get a palindrome (4636666364).

The spelling of 1221605143 in words is "one billion, two hundred twenty-one million, six hundred five thousand, one hundred forty-three".