51556661 has 6 divisors (see below), whose sum is σ = 55827810. Its totient is φ = 47590608.

The previous prime is 51556643. The next prime is 51556663. The reversal of 51556661 is 16665515.

It can be written as a sum of positive squares in 3 ways, for example, as 1416100 + 50140561 = 1190^2 + 7081^2 .

It is a de Polignac number, because none of the positive numbers 2^k-51556661 is a prime.

It is a super-3 number, since 3×51556661³ (a number of 24 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51556663) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 152366 + ... + 152703.

It is an arithmetic number, because the mean of its divisors is an integer number (9304635).

Almost surely, 2^51556661 is an apocalyptic number.

It is an amenable number.

51556661 is a deficient number, since it is larger than the sum of its proper divisors (4271149).

51556661 is a wasteful number, since it uses less digits than its factorization.

51556661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305095 (or 305082 counting only the distinct ones).

The product of its digits is 27000, while the sum is 35.

The square root of 51556661 is about 7180.2967208884. The cubic root of 51556661 is about 372.1873381960.

The spelling of 51556661 in words is "fifty-one million, five hundred fifty-six thousand, six hundred sixty-one".