51581657 has 4 divisors (see below), whose sum is σ = 51617700. Its totient is φ = 51545616.

The previous prime is 51581653. The next prime is 51581659. The reversal of 51581657 is 75618515.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 47665216 + 3916441 = 6904^2 + 1979^2 .

It is a cyclic number.

It is not a de Polignac number, because 51581657 - 2² = 51581653 is a prime.

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 51581657.

It is not an unprimeable number, because it can be changed into a prime (51581653) 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, 15782 + ... + 18767.

It is an arithmetic number, because the mean of its divisors is an integer number (12904425).

Almost surely, 2^51581657 is an apocalyptic number.

It is an amenable number.

51581657 is a deficient number, since it is larger than the sum of its proper divisors (36043).

51581657 is a wasteful number, since it uses less digits than its factorization.

51581657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36042.

The product of its digits is 42000, while the sum is 38.

The square root of 51581657 is about 7182.0371065597. The cubic root of 51581657 is about 372.2474771541.

The spelling of 51581657 in words is "fifty-one million, five hundred eighty-one thousand, six hundred fifty-seven".