1321550551 has 2 divisors, whose sum is σ = 1321550552. Its totient is φ = 1321550550.

The previous prime is 1321550513. The next prime is 1321550557. The reversal of 1321550551 is 1550551231.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1321550551 - 2²⁷ = 1187332823 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1321550557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660775275 + 660775276.

It is an arithmetic number, because the mean of its divisors is an integer number (660775276).

Almost surely, 2^1321550551 is an apocalyptic number.

1321550551 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321550551 is an equidigital number, since it uses as much as digits as its factorization.

1321550551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3750, while the sum is 28.

The square root of 1321550551 is about 36353.1367422400. The cubic root of 1321550551 is about 1097.3906612189.

The spelling of 1321550551 in words is "one billion, three hundred twenty-one million, five hundred fifty thousand, five hundred fifty-one".