51660405 has 24 divisors (see below), whose sum is σ = 90106848. Its totient is φ = 27379296.

The previous prime is 51660377. The next prime is 51660407. The reversal of 51660405 is 50406615.

51660405 = 480² + 481² + ... + 642².

It is a happy number.

51660405 is a `hidden beast` number, since 51 + 6 + 604 + 0 + 5 = 666.

It is not a de Polignac number, because 51660405 - 2¹² = 51656309 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51660407) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3814 + ... + 10856.

It is an arithmetic number, because the mean of its divisors is an integer number (3754452).

Almost surely, 2^51660405 is an apocalyptic number.

It is an amenable number.

51660405 is a deficient number, since it is larger than the sum of its proper divisors (38446443).

51660405 is a wasteful number, since it uses less digits than its factorization.

51660405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7217 (or 7214 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 51660405 is about 7187.5173043270. The cubic root of 51660405 is about 372.4368134495.

The spelling of 51660405 in words is "fifty-one million, six hundred sixty thousand, four hundred five".