51386643 has 90 divisors (see below), whose sum is σ = 99068508. Its totient is φ = 26444880.

The previous prime is 51386639. The next prime is 51386663. The reversal of 51386643 is 34668315.

51386643 is a `hidden beast` number, since 5 + 1 + 3 + 8 + 6 + 643 = 666.

It is not a de Polignac number, because 51386643 - 2² = 51386639 is a prime.

Its product of digits (51840) is a multiple of the sum of its prime divisors (128).

It is a junction number, because it is equal to n+sod(n) for n = 51386598 and 51386607.

It is not an unprimeable number, because it can be changed into a prime (51386663) by changing a digit.

It is a polite number, since it can be written in 89 ways as a sum of consecutive naturals, for example, 480196 + ... + 480302.

Almost surely, 2^51386643 is an apocalyptic number.

51386643 is a deficient number, since it is larger than the sum of its proper divisors (47681865).

51386643 is a wasteful number, since it uses less digits than its factorization.

51386643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155 (or 128 counting only the distinct ones).

The product of its digits is 51840, while the sum is 36.

The square root of 51386643 is about 7168.4477399225. The cubic root of 51386643 is about 371.7777678897. Note that the first 4 decimals are identical.

It can be divided in two parts, 5138 and 6643, that added together give a triangular number (11781 = T₁₅₃).

The spelling of 51386643 in words is "fifty-one million, three hundred eighty-six thousand, six hundred forty-three".