1321220556 has 72 divisors (see below), whose sum is σ = 3668421120. Its totient is φ = 399082464.

The previous prime is 1321220539. The next prime is 1321220573. The reversal of 1321220556 is 6550221231.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1321220539) and next prime (1321220573).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 26260 + ... + 57723.

Almost surely, 2^1321220556 is an apocalyptic number.

It is an amenable number.

1321220556 is an abundant number, since it is smaller than the sum of its proper divisors (2347200564).

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

1321220556 is a wasteful number, since it uses less digits than its factorization.

1321220556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84035 (or 84030 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 1321220556 is about 36348.5977171060. The cubic root of 1321220556 is about 1097.2993130731.

Adding to 1321220556 its reverse (6550221231), we get a palindrome (7871441787).

The spelling of 1321220556 in words is "one billion, three hundred twenty-one million, two hundred twenty thousand, five hundred fifty-six".