1211501531 has 2 divisors, whose sum is σ = 1211501532. Its totient is φ = 1211501530.

The previous prime is 1211501509. The next prime is 1211501561. The reversal of 1211501531 is 1351051121.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1211501531 - 2¹⁴ = 1211485147 is a prime.

It is a super-2 number, since 2×1211501531² = 2935471919230687922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1211501561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605750765 + 605750766.

It is an arithmetic number, because the mean of its divisors is an integer number (605750766).

Almost surely, 2^1211501531 is an apocalyptic number.

1211501531 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211501531 is an equidigital number, since it uses as much as digits as its factorization.

1211501531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 150, while the sum is 20.

The square root of 1211501531 is about 34806.6305608572. The cubic root of 1211501531 is about 1066.0428354999.

Adding to 1211501531 its reverse (1351051121), we get a palindrome (2562552652).

The spelling of 1211501531 in words is "one billion, two hundred eleven million, five hundred one thousand, five hundred thirty-one".