1551663440 has 40 divisors (see below), whose sum is σ = 3819833640. Its totient is φ = 584155136.

The previous prime is 1551663439. The next prime is 1551663493. The reversal of 1551663440 is 443661551.

It can be written as a sum of positive squares in 4 ways, for example, as 625800256 + 925863184 = 25016^2 + 30428^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 1551663440.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 569105 + ... + 571824.

It is an arithmetic number, because the mean of its divisors is an integer number (95495841).

Almost surely, 2^1551663440 is an apocalyptic number.

1551663440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1551663440 is an abundant number, since it is smaller than the sum of its proper divisors (2268170200).

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

1551663440 is a wasteful number, since it uses less digits than its factorization.

1551663440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1140959 (or 1140953 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 35.

The square root of 1551663440 is about 39391.1594142645. The cubic root of 1551663440 is about 1157.7083771034.

The spelling of 1551663440 in words is "one billion, five hundred fifty-one million, six hundred sixty-three thousand, four hundred forty".