1221545440 has 48 divisors (see below), whose sum is σ = 2934837360. Its totient is φ = 480332800.

The previous prime is 1221545383. The next prime is 1221545441. The reversal of 1221545440 is 445451221.

It is a junction number, because it is equal to n+sod(n) for n = 1221545399 and 1221545408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221545441) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55261 + ... + 74140.

It is an arithmetic number, because the mean of its divisors is an integer number (61142445).

Almost surely, 2^1221545440 is an apocalyptic number.

1221545440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221545440 is an abundant number, since it is smaller than the sum of its proper divisors (1713291920).

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

1221545440 is a wasteful number, since it uses less digits than its factorization.

1221545440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129475 (or 129467 counting only the distinct ones).

The product of its (nonzero) digits is 6400, while the sum is 28.

The square root of 1221545440 is about 34950.6143007530. The cubic root of 1221545440 is about 1068.9807279063.

Adding to 1221545440 its reverse (445451221), we get a palindrome (1666996661).

The spelling of 1221545440 in words is "one billion, two hundred twenty-one million, five hundred forty-five thousand, four hundred forty".