1211201555 has 8 divisors (see below), whose sum is σ = 1454935392. Its totient is φ = 967965568.

The previous prime is 1211201491. The next prime is 1211201591. The reversal of 1211201555 is 5551021121.

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 1211201555 - 2⁶ = 1211201491 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1211201555.

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, 119087 + ... + 128856.

It is an arithmetic number, because the mean of its divisors is an integer number (181866924).

Almost surely, 2^1211201555 is an apocalyptic number.

1211201555 is a deficient number, since it is larger than the sum of its proper divisors (243733837).

1211201555 is an equidigital number, since it uses as much as digits as its factorization.

1211201555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248925.

The product of its (nonzero) digits is 500, while the sum is 23.

The square root of 1211201555 is about 34802.3211151210. The cubic root of 1211201555 is about 1065.9548417569.

Adding to 1211201555 its reverse (5551021121), we get a palindrome (6762222676).

The spelling of 1211201555 in words is "one billion, two hundred eleven million, two hundred one thousand, five hundred fifty-five".