1221010091 has 32 divisors (see below), whose sum is σ = 1559554560. Its totient is φ = 930617856.

The previous prime is 1221010081. The next prime is 1221010097. The reversal of 1221010091 is 1900101221.

It is not a de Polignac number, because 1221010091 - 2²⁶ = 1153901227 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221010097) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1476020 + ... + 1476846.

It is an arithmetic number, because the mean of its divisors is an integer number (48736080).

Almost surely, 2^1221010091 is an apocalyptic number.

1221010091 is a deficient number, since it is larger than the sum of its proper divisors (338544469).

1221010091 is a wasteful number, since it uses less digits than its factorization.

1221010091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1523.

The product of its (nonzero) digits is 36, while the sum is 17.

The square root of 1221010091 is about 34942.9548120934. The cubic root of 1221010091 is about 1068.8245428622.

The spelling of 1221010091 in words is "one billion, two hundred twenty-one million, ten thousand, ninety-one".