51505661 has 8 divisors (see below), whose sum is σ = 52698360. Its totient is φ = 50326272.

The previous prime is 51505621. The next prime is 51505669. The reversal of 51505661 is 16650515.

It can be written as a sum of positive squares in 4 ways, for example, as 6280036 + 45225625 = 2506^2 + 6725^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51505661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51505669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4721 + ... + 11193.

It is an arithmetic number, because the mean of its divisors is an integer number (6587295).

Almost surely, 2^51505661 is an apocalyptic number.

It is an amenable number.

51505661 is a deficient number, since it is larger than the sum of its proper divisors (1192699).

51505661 is a wasteful number, since it uses less digits than its factorization.

51505661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6655.

The product of its (nonzero) digits is 4500, while the sum is 29.

The square root of 51505661 is about 7176.7444569247. The cubic root of 51505661 is about 372.0645747729.

The spelling of 51505661 in words is "fifty-one million, five hundred five thousand, six hundred sixty-one".