51161463721 has 3 divisors (see below), whose sum is σ = 51161689911. Its totient is φ = 51161237532.

The previous prime is 51161463713. The next prime is 51161463751. The reversal of 51161463721 is 12736416115.

The square root of 51161463721 is 226189.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 44095380121 + 7066083600 = 209989^2 + 84060^2 .

It is not a de Polignac number, because 51161463721 - 2³ = 51161463713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51161463701) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 113095 + ... + 339283.

It is an arithmetic number, because the mean of its divisors is an integer number (17053896637).

Almost surely, 2^51161463721 is an apocalyptic number.

51161463721 is the 226189-th square number.

51161463721 is the 113095-th centered octagonal number.

It is an amenable number.

51161463721 is a deficient number, since it is larger than the sum of its proper divisors (226190).

51161463721 is an frugal number, since it uses more digits than its factorization.

51161463721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 452378 (or 226189 counting only the distinct ones).

The product of its digits is 30240, while the sum is 37.

Adding to 51161463721 its reverse (12736416115), we get a palindrome (63897879836).

The spelling of 51161463721 in words is "fifty-one billion, one hundred sixty-one million, four hundred sixty-three thousand, seven hundred twenty-one".