1221320951 has 2 divisors, whose sum is σ = 1221320952. Its totient is φ = 1221320950.

The previous prime is 1221320941. The next prime is 1221321001. The reversal of 1221320951 is 1590231221.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221320951 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1221320951.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221320921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610660475 + 610660476.

It is an arithmetic number, because the mean of its divisors is an integer number (610660476).

Almost surely, 2^1221320951 is an apocalyptic number.

1221320951 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221320951 is an equidigital number, since it uses as much as digits as its factorization.

1221320951 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 1221320951 is about 34947.4026359614. The cubic root of 1221320951 is about 1068.9152400665.

The spelling of 1221320951 in words is "one billion, two hundred twenty-one million, three hundred twenty thousand, nine hundred fifty-one".