1221143565 has 8 divisors (see below), whose sum is σ = 1953829728. Its totient is φ = 651276560.

The previous prime is 1221143551. The next prime is 1221143587. The reversal of 1221143565 is 5653411221.

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

It is not a de Polignac number, because 1221143565 - 2⁷ = 1221143437 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40704771 + ... + 40704800.

It is an arithmetic number, because the mean of its divisors is an integer number (244228716).

Almost surely, 2^1221143565 is an apocalyptic number.

1221143565 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1221143565 is a deficient number, since it is larger than the sum of its proper divisors (732686163).

1221143565 is an equidigital number, since it uses as much as digits as its factorization.

1221143565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81409579.

The product of its digits is 7200, while the sum is 30.

The square root of 1221143565 is about 34944.8646441791. The cubic root of 1221143565 is about 1068.8634874186.

Adding to 1221143565 its reverse (5653411221), we get a palindrome (6874554786).

The spelling of 1221143565 in words is "one billion, two hundred twenty-one million, one hundred forty-three thousand, five hundred sixty-five".