1211157505 has 4 divisors (see below), whose sum is σ = 1453389012. Its totient is φ = 968926000.

The previous prime is 1211157499. The next prime is 1211157517. The reversal of 1211157505 is 5057511121.

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

It can be written as a sum of positive squares in 2 ways, for example, as 590101264 + 621056241 = 24292^2 + 24921^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1211157505 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121115746 + ... + 121115755.

It is an arithmetic number, because the mean of its divisors is an integer number (363347253).

Almost surely, 2^1211157505 is an apocalyptic number.

It is an amenable number.

1211157505 is a deficient number, since it is larger than the sum of its proper divisors (242231507).

1211157505 is an equidigital number, since it uses as much as digits as its factorization.

1211157505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242231506.

The product of its (nonzero) digits is 1750, while the sum is 28.

The square root of 1211157505 is about 34801.6882492789. The cubic root of 1211157505 is about 1065.9419190852.

Adding to 1211157505 its reverse (5057511121), we get a palindrome (6268668626).

The spelling of 1211157505 in words is "one billion, two hundred eleven million, one hundred fifty-seven thousand, five hundred five".