1220155551 has 12 divisors (see below), whose sum is σ = 1771395912. Its totient is φ = 809306736.

The previous prime is 1220155537. The next prime is 1220155627. The reversal of 1220155551 is 1555510221.

It is not a de Polignac number, because 1220155551 - 2⁷ = 1220155423 is a prime.

It is a super-2 number, since 2×1220155551² = 2977559137272227202, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1220155051) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 342321 + ... + 345866.

It is an arithmetic number, because the mean of its divisors is an integer number (147616326).

Almost surely, 2^1220155551 is an apocalyptic number.

1220155551 is a deficient number, since it is larger than the sum of its proper divisors (551240361).

1220155551 is a wasteful number, since it uses less digits than its factorization.

1220155551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 688390 (or 688387 counting only the distinct ones).

The product of its (nonzero) digits is 2500, while the sum is 27.

The square root of 1220155551 is about 34930.7250282613. The cubic root of 1220155551 is about 1068.5751410244.

Adding to 1220155551 its reverse (1555510221), we get a palindrome (2775665772).

The spelling of 1220155551 in words is "one billion, two hundred twenty million, one hundred fifty-five thousand, five hundred fifty-one".