51686890 has 16 divisors (see below), whose sum is σ = 93512232. Its totient is φ = 20569024.

The previous prime is 51686879. The next prime is 51686893. The reversal of 51686890 is 9868615.

It can be written as a sum of positive squares in 4 ways, for example, as 45738169 + 5948721 = 6763^2 + 2439^2 .

It is not an unprimeable number, because it can be changed into a prime (51686893) 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, 11149 + ... + 15088.

Almost surely, 2^51686890 is an apocalyptic number.

51686890 is a deficient number, since it is larger than the sum of its proper divisors (41825342).

51686890 is a wasteful number, since it uses less digits than its factorization.

51686890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26441.

The product of its (nonzero) digits is 103680, while the sum is 43.

The square root of 51686890 is about 7189.3594985923. The cubic root of 51686890 is about 372.5004489282.

The spelling of 51686890 in words is "fifty-one million, six hundred eighty-six thousand, eight hundred ninety".