1212121221 has 16 divisors (see below), whose sum is σ = 1667001024. Its totient is φ = 782849664.

The previous prime is 1212121219. The next prime is 1212121231. The reversal of 1212121221 is 1221212121.

It is not a de Polignac number, because 1212121221 - 2¹ = 1212121219 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1212121221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1212121231) 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, 2430 + ... + 49296.

It is an arithmetic number, because the mean of its divisors is an integer number (104187564).

Almost surely, 2^1212121221 is an apocalyptic number.

It is an amenable number.

1212121221 is a deficient number, since it is larger than the sum of its proper divisors (454879803).

1212121221 is a wasteful number, since it uses less digits than its factorization.

1212121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47140.

The product of its digits is 32, while the sum is 15.

The square root of 1212121221 is about 34815.5313186515. The cubic root of 1212121221 is about 1066.2245668648.

Adding to 1212121221 its reverse (1221212121), we get a palindrome (2433333342).

It can be divided in two parts, 12121212 and 21, that multiplied together give a palindrome (254545452).

The spelling of 1212121221 in words is "one billion, two hundred twelve million, one hundred twenty-one thousand, two hundred twenty-one".