1221256040 has 64 divisors (see below), whose sum is σ = 2828846160. Its totient is φ = 474163200.

The previous prime is 1221256031. The next prime is 1221256063. The reversal of 1221256040 is 406521221.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 1208396644 + 12859396 = 34762^2 + 3586^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1221255997 and 1221256015.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 888794 + ... + 890166.

Almost surely, 2^1221256040 is an apocalyptic number.

1221256040 is a gapful number since it is divisible by the number (10) 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 1221256040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1414423080).

1221256040 is an abundant number, since it is smaller than the sum of its proper divisors (1607590120).

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

1221256040 is a wasteful number, since it uses less digits than its factorization.

1221256040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2022 (or 2018 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 1221256040 is about 34946.4739279945. The cubic root of 1221256040 is about 1068.8963027603.

Adding to 1221256040 its reverse (406521221), we get a palindrome (1627777261).

The spelling of 1221256040 in words is "one billion, two hundred twenty-one million, two hundred fifty-six thousand, forty".