51381986 has 4 divisors (see below), whose sum is σ = 77072982. Its totient is φ = 25690992.

The previous prime is 51381983. The next prime is 51382013. The reversal of 51381986 is 68918315.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 68918315 = 5 ⋅13783663.

It can be written as a sum of positive squares in only one way, i.e., 33582025 + 17799961 = 5795^2 + 4219^2 .

It is not an unprimeable number, because it can be changed into a prime (51381983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12845495 + ... + 12845498.

Almost surely, 2^51381986 is an apocalyptic number.

51381986 is a deficient number, since it is larger than the sum of its proper divisors (25690996).

51381986 is a wasteful number, since it uses less digits than its factorization.

51381986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25690995.

The product of its digits is 51840, while the sum is 41.

The square root of 51381986 is about 7168.1229063124. The cubic root of 51381986 is about 371.7665365576.

The spelling of 51381986 in words is "fifty-one million, three hundred eighty-one thousand, nine hundred eighty-six".