1221501011 has 2 divisors, whose sum is σ = 1221501012. Its totient is φ = 1221501010.

The previous prime is 1221501007. The next prime is 1221501019. The reversal of 1221501011 is 1101051221.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1221501011 - 2² = 1221501007 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221501019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610750505 + 610750506.

It is an arithmetic number, because the mean of its divisors is an integer number (610750506).

Almost surely, 2^1221501011 is an apocalyptic number.

1221501011 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221501011 is an equidigital number, since it uses as much as digits as its factorization.

1221501011 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20, while the sum is 14.

The square root of 1221501011 is about 34949.9786981337. The cubic root of 1221501011 is about 1068.9677677334.

Adding to 1221501011 its reverse (1101051221), we get a palindrome (2322552232).

The spelling of 1221501011 in words is "one billion, two hundred twenty-one million, five hundred one thousand, eleven".