1211204551 has 4 divisors (see below), whose sum is σ = 1213692112. Its totient is φ = 1208716992.

The previous prime is 1211204543. The next prime is 1211204567. The reversal of 1211204551 is 1554021121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1554021121 = 631 ⋅2462791.

It is a cyclic number.

It is not a de Polignac number, because 1211204551 - 2³ = 1211204543 is a prime.

It is a super-2 number, since 2×1211204551² = 2934032928726223202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211204531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1243050 + ... + 1244023.

It is an arithmetic number, because the mean of its divisors is an integer number (303423028).

Almost surely, 2^1211204551 is an apocalyptic number.

1211204551 is a deficient number, since it is larger than the sum of its proper divisors (2487561).

1211204551 is an equidigital number, since it uses as much as digits as its factorization.

1211204551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2487560.

The product of its (nonzero) digits is 400, while the sum is 22.

The square root of 1211204551 is about 34802.3641582005. The cubic root of 1211204551 is about 1065.9557206632.

Adding to 1211204551 its reverse (1554021121), we get a palindrome (2765225672).

The spelling of 1211204551 in words is "one billion, two hundred eleven million, two hundred four thousand, five hundred fifty-one".