1221608636 has 12 divisors (see below), whose sum is σ = 2139342240. Its totient is φ = 610368000.

The previous prime is 1221608617. The next prime is 1221608657. The reversal of 1221608636 is 6368061221.

It is a junction number, because it is equal to n+sod(n) for n = 1221608596 and 1221608605.

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, 102740 + ... + 114011.

It is an arithmetic number, because the mean of its divisors is an integer number (178278520).

Almost surely, 2^1221608636 is an apocalyptic number.

It is an amenable number.

1221608636 is a deficient number, since it is larger than the sum of its proper divisors (917733604).

1221608636 is a wasteful number, since it uses less digits than its factorization.

1221608636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218164 (or 218162 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 1221608636 is about 34951.5183647292. The cubic root of 1221608636 is about 1068.9991619705. Note that the first 3 decimals are identical.

Adding to 1221608636 its reverse (6368061221), we get a palindrome (7589669857).

The spelling of 1221608636 in words is "one billion, two hundred twenty-one million, six hundred eight thousand, six hundred thirty-six".