51011861 has 4 divisors (see below), whose sum is σ = 53229792. Its totient is φ = 48793932.

The previous prime is 51011839. The next prime is 51011869. The reversal of 51011861 is 16811015.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51011861 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 2217907 = 51011861 / (5 + 1 + 0 + 1 + 1 + 8 + 6 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51011869) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1108931 + ... + 1108976.

It is an arithmetic number, because the mean of its divisors is an integer number (13307448).

Almost surely, 2^51011861 is an apocalyptic number.

It is an amenable number.

51011861 is a deficient number, since it is larger than the sum of its proper divisors (2217931).

51011861 is a wasteful number, since it uses less digits than its factorization.

51011861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2217930.

The product of its (nonzero) digits is 240, while the sum is 23.

The square root of 51011861 is about 7142.2588163690. The cubic root of 51011861 is about 370.8717235123.

Adding to 51011861 its reverse (16811015), we get a palindrome (67822876).

The spelling of 51011861 in words is "fifty-one million, eleven thousand, eight hundred sixty-one".