1221505144 has 8 divisors (see below), whose sum is σ = 2290322160. Its totient is φ = 610752568.

The previous prime is 1221505123. The next prime is 1221505147. The reversal of 1221505144 is 4415051221.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221505147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 76344064 + ... + 76344079.

It is an arithmetic number, because the mean of its divisors is an integer number (286290270).

Almost surely, 2^1221505144 is an apocalyptic number.

It is an amenable number.

1221505144 is a deficient number, since it is larger than the sum of its proper divisors (1068817016).

1221505144 is a wasteful number, since it uses less digits than its factorization.

1221505144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152688149 (or 152688145 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 25.

The square root of 1221505144 is about 34950.0378254445. The cubic root of 1221505144 is about 1068.9689733645.

Adding to 1221505144 its reverse (4415051221), we get a palindrome (5636556365).

The spelling of 1221505144 in words is "one billion, two hundred twenty-one million, five hundred five thousand, one hundred forty-four".