1221510121 has 16 divisors (see below), whose sum is σ = 1328723200. Its totient is φ = 1116244800.

The previous prime is 1221510109. The next prime is 1221510127. The reversal of 1221510121 is 1210151221.

It is a cyclic number.

It is not a de Polignac number, because 1221510121 - 2¹¹ = 1221508073 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221510095 and 1221510104.

It is not an unprimeable number, because it can be changed into a prime (1221510127) 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, 684196 + ... + 685978.

It is an arithmetic number, because the mean of its divisors is an integer number (83045200).

Almost surely, 2^1221510121 is an apocalyptic number.

It is an amenable number.

1221510121 is a deficient number, since it is larger than the sum of its proper divisors (107213079).

1221510121 is a wasteful number, since it uses less digits than its factorization.

1221510121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2296.

The product of its (nonzero) digits is 40, while the sum is 16.

The square root of 1221510121 is about 34950.1090270116. The cubic root of 1221510121 is about 1068.9704251939.

Adding to 1221510121 its reverse (1210151221), we get a palindrome (2431661342).

The spelling of 1221510121 in words is "one billion, two hundred twenty-one million, five hundred ten thousand, one hundred twenty-one".