1551661656 has 32 divisors (see below), whose sum is σ = 3883430400. Its totient is φ = 516650400.

The previous prime is 1551661651. The next prime is 1551661663. The reversal of 1551661656 is 6561661551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1551661651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13120 + ... + 57231.

It is an arithmetic number, because the mean of its divisors is an integer number (121357200).

Almost surely, 2^1551661656 is an apocalyptic number.

It is an amenable number.

1551661656 is an abundant number, since it is smaller than the sum of its proper divisors (2331768744).

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

1551661656 is a wasteful number, since it uses less digits than its factorization.

1551661656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71279 (or 71275 counting only the distinct ones).

The product of its digits is 162000, while the sum is 42.

The square root of 1551661656 is about 39391.1367695831. The cubic root of 1551661656 is about 1157.7079334177.

The spelling of 1551661656 in words is "one billion, five hundred fifty-one million, six hundred sixty-one thousand, six hundred fifty-six".