51881561 has 4 divisors (see below), whose sum is σ = 52985472. Its totient is φ = 50777652.

The previous prime is 51881527. The next prime is 51881567. The reversal of 51881561 is 16518815.

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 not a de Polignac number, because 51881561 - 2⁶ = 51881497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51881567) 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, 551885 + ... + 551978.

It is an arithmetic number, because the mean of its divisors is an integer number (13246368).

Almost surely, 2^51881561 is an apocalyptic number.

It is an amenable number.

51881561 is a deficient number, since it is larger than the sum of its proper divisors (1103911).

51881561 is a wasteful number, since it uses less digits than its factorization.

51881561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1103910.

The product of its digits is 9600, while the sum is 35.

The square root of 51881561 is about 7202.8856023125. The cubic root of 51881561 is about 372.9675189200.

The spelling of 51881561 in words is "fifty-one million, eight hundred eighty-one thousand, five hundred sixty-one".