1220855581 has 4 divisors (see below), whose sum is σ = 1331842464. Its totient is φ = 1109868700.

The previous prime is 1220855551. The next prime is 1220855599. The reversal of 1220855581 is 1855580221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1220855581 - 2¹³ = 1220847389 is a prime.

It is a super-2 number, since 2×1220855581² = 2980976699317695122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1220855581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1220855501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55493425 + ... + 55493446.

It is an arithmetic number, because the mean of its divisors is an integer number (332960616).

Almost surely, 2^1220855581 is an apocalyptic number.

1220855581 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1220855581 is a deficient number, since it is larger than the sum of its proper divisors (110986883).

1220855581 is a wasteful number, since it uses less digits than its factorization.

1220855581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110986882.

The product of its (nonzero) digits is 32000, while the sum is 37.

The square root of 1220855581 is about 34940.7438529863. The cubic root of 1220855581 is about 1068.7794569540.

The spelling of 1220855581 in words is "one billion, two hundred twenty million, eight hundred fifty-five thousand, five hundred eighty-one".