1211201591 has 2 divisors, whose sum is σ = 1211201592. Its totient is φ = 1211201590.

The previous prime is 1211201491. The next prime is 1211201611. The reversal of 1211201591 is 1951021121.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1211201591 - 2¹⁸ = 1210939447 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211201291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605600795 + 605600796.

It is an arithmetic number, because the mean of its divisors is an integer number (605600796).

Almost surely, 2^1211201591 is an apocalyptic number.

1211201591 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211201591 is an equidigital number, since it uses as much as digits as its factorization.

1211201591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 180, while the sum is 23.

The square root of 1211201591 is about 34802.3216323279. The cubic root of 1211201591 is about 1065.9548523179.

The spelling of 1211201591 in words is "one billion, two hundred eleven million, two hundred one thousand, five hundred ninety-one".