51981908649 has 8 divisors (see below), whose sum is σ = 75610048992. Its totient is φ = 31504187040.

The previous prime is 51981908639. The next prime is 51981908669. The reversal of 51981908649 is 94680918915.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 51981908649 - 2³² = 47686941353 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 51981908592 and 51981908601.

It is not an unprimeable number, because it can be changed into a prime (51981908639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 787604644 + ... + 787604709.

It is an arithmetic number, because the mean of its divisors is an integer number (9451256124).

Almost surely, 2^51981908649 is an apocalyptic number.

It is an amenable number.

51981908649 is a deficient number, since it is larger than the sum of its proper divisors (23628140343).

51981908649 is a wasteful number, since it uses less digits than its factorization.

51981908649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1575209367.

The product of its (nonzero) digits is 5598720, while the sum is 60.

The spelling of 51981908649 in words is "fifty-one billion, nine hundred eighty-one million, nine hundred eight thousand, six hundred forty-nine".