51391786 has 4 divisors (see below), whose sum is σ = 77087682. Its totient is φ = 25695892.

The previous prime is 51391771. The next prime is 51391787. The reversal of 51391786 is 68719315.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 48930025 + 2461761 = 6995^2 + 1569^2 .

It is a super-2 number, since 2×51391786² = 5282231336539592, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (51391787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12847945 + ... + 12847948.

Almost surely, 2^51391786 is an apocalyptic number.

51391786 is a deficient number, since it is larger than the sum of its proper divisors (25695896).

51391786 is a wasteful number, since it uses less digits than its factorization.

51391786 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25695895.

The product of its digits is 45360, while the sum is 40.

The square root of 51391786 is about 7168.8064557498. The cubic root of 51391786 is about 371.7901705244.

The spelling of 51391786 in words is "fifty-one million, three hundred ninety-one thousand, seven hundred eighty-six".