1221642240 has 768 divisors, whose sum is σ = 5283532800. Its totient is φ = 233570304.

The previous prime is 1221642211. The next prime is 1221642251. The reversal of 1221642240 is 422461221.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (768).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 1221642240.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 53114869 + ... + 53114891.

It is an arithmetic number, because the mean of its divisors is an integer number (6879600).

Almost surely, 2^1221642240 is an apocalyptic number.

1221642240 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 1221642240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2641766400).

1221642240 is an abundant number, since it is smaller than the sum of its proper divisors (4061890560).

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

1221642240 is a wasteful number, since it uses less digits than its factorization.

1221642240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92 (or 72 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 1221642240 is about 34951.9990844587. Note that the first 3 decimals coincide. The cubic root of 1221642240 is about 1069.0089638873.

The spelling of 1221642240 in words is "one billion, two hundred twenty-one million, six hundred forty-two thousand, two hundred forty".