1221205101 has 16 divisors (see below), whose sum is σ = 1661554560. Its totient is φ = 797644800.

The previous prime is 1221205093. The next prime is 1221205159. The reversal of 1221205101 is 1015021221.

It is not a de Polignac number, because 1221205101 - 2³ = 1221205093 is a prime.

It is a super-3 number, since 3×1221205101³ (a number of 28 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221205901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14605 + ... + 51533.

It is an arithmetic number, because the mean of its divisors is an integer number (103847160).

Almost surely, 2^1221205101 is an apocalyptic number.

It is an amenable number.

1221205101 is a deficient number, since it is larger than the sum of its proper divisors (440349459).

1221205101 is a wasteful number, since it uses less digits than its factorization.

1221205101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37156.

The product of its (nonzero) digits is 40, while the sum is 15.

The square root of 1221205101 is about 34945.7451058065. The cubic root of 1221205101 is about 1068.8814412123.

Adding to 1221205101 its reverse (1015021221), we get a palindrome (2236226322).

The spelling of 1221205101 in words is "one billion, two hundred twenty-one million, two hundred five thousand, one hundred one".