51961909988521 has 45 divisors (see below), whose sum is σ = 58242933767205. Its totient is φ = 46337140661760.

The previous prime is 51961909988497. The next prime is 51961909988557. The reversal of 51961909988521 is 12588990916915.

The square root of 51961909988521 is 7208461.

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

It can be written as a sum of positive squares in 4 ways, for example, as 4881178816921 + 47080731171600 = 2209339^2 + 6861540^2 .

It is not a de Polignac number, because 51961909988521 - 2¹³ = 51961909980329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51961909988581) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 90055302985 + ... + 90055303561.

It is an arithmetic number, because the mean of its divisors is an integer number (1294287417049).

Almost surely, 2^{51961909988521} is an apocalyptic number.

51961909988521 is the 7208461-st square number.

51961909988521 is the 3604231-st centered octagonal number.

It is an amenable number.

51961909988521 is a deficient number, since it is larger than the sum of its proper divisors (6281023778684).

51961909988521 is an frugal number, since it uses more digits than its factorization.

51961909988521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1304 (or 621 counting only the distinct ones).

The product of its (nonzero) digits is 125971200, while the sum is 73.

The spelling of 51961909988521 in words is "fifty-one trillion, nine hundred sixty-one billion, nine hundred nine million, nine hundred eighty-eight thousand, five hundred twenty-one".