1215311551 has 2 divisors, whose sum is σ = 1215311552. Its totient is φ = 1215311550.

The previous prime is 1215311533. The next prime is 1215311557. The reversal of 1215311551 is 1551135121.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1215311551 - 2⁷ = 1215311423 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1215311557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 607655775 + 607655776.

It is an arithmetic number, because the mean of its divisors is an integer number (607655776).

Almost surely, 2^1215311551 is an apocalyptic number.

1215311551 is a deficient number, since it is larger than the sum of its proper divisors (1).

1215311551 is an equidigital number, since it uses as much as digits as its factorization.

1215311551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 750, while the sum is 25.

The square root of 1215311551 is about 34861.3188362116. The cubic root of 1215311551 is about 1067.1591896155.

Adding to 1215311551 its reverse (1551135121), we get a palindrome (2766446672).

The spelling of 1215311551 in words is "one billion, two hundred fifteen million, three hundred eleven thousand, five hundred fifty-one".