51381561 has 48 divisors (see below), whose sum is σ = 87554432. Its totient is φ = 26231040.

The previous prime is 51381557. The next prime is 51381587. The reversal of 51381561 is 16518315.

It is not a de Polignac number, because 51381561 - 2² = 51381557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51381661) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 185355 + ... + 185631.

Almost surely, 2^51381561 is an apocalyptic number.

It is an amenable number.

51381561 is a deficient number, since it is larger than the sum of its proper divisors (36172871).

51381561 is a wasteful number, since it uses less digits than its factorization.

51381561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 382 (or 371 counting only the distinct ones).

The product of its digits is 3600, while the sum is 30.

The square root of 51381561 is about 7168.0932611121. The cubic root of 51381561 is about 371.7655115471.

Adding to 51381561 its reverse (16518315), we get a palindrome (67899876).

The spelling of 51381561 in words is "fifty-one million, three hundred eighty-one thousand, five hundred sixty-one".