1221105511 has 4 divisors (see below), whose sum is σ = 1229301000. Its totient is φ = 1212910024.

The previous prime is 1221105493. The next prime is 1221105539. The reversal of 1221105511 is 1155011221.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1221105511 - 2⁹ = 1221104999 is a prime.

It is a super-2 number, since 2×1221105511² = 2982197337989142242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221105541) 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, 4097521 + ... + 4097818.

It is an arithmetic number, because the mean of its divisors is an integer number (307325250).

Almost surely, 2^1221105511 is an apocalyptic number.

1221105511 is a deficient number, since it is larger than the sum of its proper divisors (8195489).

1221105511 is an equidigital number, since it uses as much as digits as its factorization.

1221105511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8195488.

The product of its (nonzero) digits is 100, while the sum is 19.

The square root of 1221105511 is about 34944.3201536387. The cubic root of 1221105511 is about 1068.8523844506.

Adding to 1221105511 its reverse (1155011221), we get a palindrome (2376116732).

The spelling of 1221105511 in words is "one billion, two hundred twenty-one million, one hundred five thousand, five hundred eleven".