1221023644 has 12 divisors (see below), whose sum is σ = 2173008600. Its totient is φ = 600164048.

The previous prime is 1221023633. The next prime is 1221023653. The reversal of 1221023644 is 4463201221.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2586679 + ... + 2587150.

It is an arithmetic number, because the mean of its divisors is an integer number (181084050).

Almost surely, 2^1221023644 is an apocalyptic number.

It is an amenable number.

1221023644 is a deficient number, since it is larger than the sum of its proper divisors (951984956).

1221023644 is a wasteful number, since it uses less digits than its factorization.

1221023644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5173892 (or 5173890 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 1221023644 is about 34943.1487419208. The cubic root of 1221023644 is about 1068.8284974365.

Adding to 1221023644 its reverse (4463201221), we get a palindrome (5684224865).

The spelling of 1221023644 in words is "one billion, two hundred twenty-one million, twenty-three thousand, six hundred forty-four".