1221747840 has 256 divisors, whose sum is σ = 4582656000. Its totient is φ = 306561024.

The previous prime is 1221747829. The next prime is 1221747841. The reversal of 1221747840 is 487471221.

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

It is a junction number, because it is equal to n+sod(n) for n = 1221747795 and 1221747804.

It is not an unprimeable number, because it can be changed into a prime (1221747841) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 291681 + ... + 295839.

It is an arithmetic number, because the mean of its divisors is an integer number (17901000).

Almost surely, 2^1221747840 is an apocalyptic number.

1221747840 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 1221747840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2291328000).

1221747840 is an abundant number, since it is smaller than the sum of its proper divisors (3360908160).

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

1221747840 is a wasteful number, since it uses less digits than its factorization.

1221747840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4204 (or 4186 counting only the distinct ones).

The product of its (nonzero) digits is 25088, while the sum is 36.

The square root of 1221747840 is about 34953.5096950220. The cubic root of 1221747840 is about 1069.0397650745.

The spelling of 1221747840 in words is "one billion, two hundred twenty-one million, seven hundred forty-seven thousand, eight hundred forty".