1221021155 has 8 divisors (see below), whose sum is σ = 1492871472. Its totient is φ = 958386208.

The previous prime is 1221021119. The next prime is 1221021173. The reversal of 1221021155 is 5511201221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221021155 - 2³⁰ = 147279331 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2303549 + ... + 2304078.

It is an arithmetic number, because the mean of its divisors is an integer number (186608934).

Almost surely, 2^1221021155 is an apocalyptic number.

1221021155 is a deficient number, since it is larger than the sum of its proper divisors (271850317).

1221021155 is an equidigital number, since it uses as much as digits as its factorization.

1221021155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4607685.

The product of its (nonzero) digits is 200, while the sum is 20.

The square root of 1221021155 is about 34943.1131269096. The cubic root of 1221021155 is about 1068.8277711836.

Adding to 1221021155 its reverse (5511201221), we get a palindrome (6732222376).

The spelling of 1221021155 in words is "one billion, two hundred twenty-one million, twenty-one thousand, one hundred fifty-five".