1221606144 has 144 divisors (see below), whose sum is σ = 3941159040. Its totient is φ = 370160640.

The previous prime is 1221606137. The next prime is 1221606149. The reversal of 1221606144 is 4416061221.

1221606144 is a `hidden beast` number, since 12 + 2 + 1 + 606 + 1 + 44 = 666.

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

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (1221606149) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 67999 + ... + 84065.

It is an arithmetic number, because the mean of its divisors is an integer number (27369160).

Almost surely, 2^1221606144 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221606144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1970579520).

1221606144 is an abundant number, since it is smaller than the sum of its proper divisors (2719552896).

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

1221606144 is a wasteful number, since it uses less digits than its factorization.

1221606144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16103 (or 16083 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 1221606144 is about 34951.4827153298. The cubic root of 1221606144 is about 1068.9984350744.

Adding to 1221606144 its reverse (4416061221), we get a palindrome (5637667365).

The spelling of 1221606144 in words is "one billion, two hundred twenty-one million, six hundred six thousand, one hundred forty-four".