1221515412 has 48 divisors (see below), whose sum is σ = 3099879552. Its totient is φ = 372124800.

The previous prime is 1221515389. The next prime is 1221515417. The reversal of 1221515412 is 2145151221.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221515417) 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, 23008 + ... + 54519.

It is an arithmetic number, because the mean of its divisors is an integer number (64580824).

Almost surely, 2^1221515412 is an apocalyptic number.

1221515412 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1221515412 is an abundant number, since it is smaller than the sum of its proper divisors (1878364140).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221515412 is a wasteful number, since it uses less digits than its factorization.

1221515412 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77648 (or 77646 counting only the distinct ones).

The product of its digits is 800, while the sum is 24.

The square root of 1221515412 is about 34950.1847205419. The cubic root of 1221515412 is about 1068.9719686152.

Adding to 1221515412 its reverse (2145151221), we get a palindrome (3366666633).

The spelling of 1221515412 in words is "one billion, two hundred twenty-one million, five hundred fifteen thousand, four hundred twelve".