1221512445 has 12 divisors (see below), whose sum is σ = 2117288316. Its totient is φ = 651473280.

The previous prime is 1221512419. The next prime is 1221512477. The reversal of 1221512445 is 5442151221.

It is a happy number.

1221512445 is a `hidden beast` number, since 1 + 2 + 215 + 1 + 2 + 445 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 713370681 + 508141764 = 26709^2 + 22542^2 .

It is not a de Polignac number, because 1221512445 - 2⁶ = 1221512381 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13572316 + ... + 13572405.

It is an arithmetic number, because the mean of its divisors is an integer number (176440693).

Almost surely, 2^1221512445 is an apocalyptic number.

1221512445 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1221512445 is a deficient number, since it is larger than the sum of its proper divisors (895775871).

1221512445 is a wasteful number, since it uses less digits than its factorization.

1221512445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27144732 (or 27144729 counting only the distinct ones).

The product of its digits is 3200, while the sum is 27.

The square root of 1221512445 is about 34950.1422743885. The cubic root of 1221512445 is about 1068.9711031213.

Adding to 1221512445 its reverse (5442151221), we get a palindrome (6663663666).

The spelling of 1221512445 in words is "one billion, two hundred twenty-one million, five hundred twelve thousand, four hundred forty-five".