1221110001 has 48 divisors (see below), whose sum is σ = 1873295424. Its totient is φ = 765459072.

The previous prime is 1221109973. The next prime is 1221110071. The reversal of 1221110001 is 1000111221.

It is a happy number.

It is not a de Polignac number, because 1221110001 - 2⁶ = 1221109937 is a prime.

It is a super-2 number, since 2×1221110001² = 2982219269084440002, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1221110071) 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 in 47 ways as a sum of consecutive naturals, for example, 1531735 + ... + 1532531.

It is an arithmetic number, because the mean of its divisors is an integer number (39026988).

Almost surely, 2^1221110001 is an apocalyptic number.

It is an amenable number.

1221110001 is a deficient number, since it is larger than the sum of its proper divisors (652185423).

1221110001 is a wasteful number, since it uses less digits than its factorization.

1221110001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 990 (or 987 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

The square root of 1221110001 is about 34944.3843986412. The cubic root of 1221110001 is about 1068.8536945043.

Adding to 1221110001 its reverse (1000111221), we get a palindrome (2221221222).

The spelling of 1221110001 in words is "one billion, two hundred twenty-one million, one hundred ten thousand, one".