1221718752 has 144 divisors (see below), whose sum is σ = 3632428800. Its totient is φ = 389120256.

The previous prime is 1221718747. The next prime is 1221718769. The reversal of 1221718752 is 2578171221.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 580999 + ... + 583097.

It is an arithmetic number, because the mean of its divisors is an integer number (25225200).

Almost surely, 2^1221718752 is an apocalyptic number.

1221718752 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221718752, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1816214400).

1221718752 is an abundant number, since it is smaller than the sum of its proper divisors (2410710048).

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

1221718752 is a wasteful number, since it uses less digits than its factorization.

1221718752 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2205 (or 2194 counting only the distinct ones).

The product of its digits is 15680, while the sum is 36.

The square root of 1221718752 is about 34953.0935969908. The cubic root of 1221718752 is about 1069.0312809246.

Adding to 1221718752 its reverse (2578171221), we get a palindrome (3799889973).

The spelling of 1221718752 in words is "one billion, two hundred twenty-one million, seven hundred eighteen thousand, seven hundred fifty-two".