1221455011 has 4 divisors (see below), whose sum is σ = 1395948592. Its totient is φ = 1046961432.

The previous prime is 1221455003. The next prime is 1221455021. The reversal of 1221455011 is 1105541221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1105541221 = 4159 ⋅265819.

It is a cyclic number.

It is not a de Polignac number, because 1221455011 - 2³ = 1221455003 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221455021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 87246780 + ... + 87246793.

It is an arithmetic number, because the mean of its divisors is an integer number (348987148).

Almost surely, 2^1221455011 is an apocalyptic number.

1221455011 is a deficient number, since it is larger than the sum of its proper divisors (174493581).

1221455011 is an equidigital number, since it uses as much as digits as its factorization.

1221455011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174493580.

The product of its (nonzero) digits is 400, while the sum is 22.

The square root of 1221455011 is about 34949.3206085612. The cubic root of 1221455011 is about 1068.9543489603.

Adding to 1221455011 its reverse (1105541221), we get a palindrome (2326996232).

The spelling of 1221455011 in words is "one billion, two hundred twenty-one million, four hundred fifty-five thousand, eleven".