51491451648 has 216 divisors, whose sum is σ = 171681062448. Its totient is φ = 13580034048.

The previous prime is 51491451631. The next prime is 51491451659. The reversal of 51491451648 is 84615419415.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a junction number, because it is equal to n+sod(n) for n = 51491451597 and 51491451606.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 436590 + ... + 541842.

Almost surely, 2^51491451648 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51491451648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (85840531224).

51491451648 is an abundant number, since it is smaller than the sum of its proper divisors (120189610800).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51491451648 is a wasteful number, since it uses less digits than its factorization.

51491451648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105299 (or 105278 counting only the distinct ones).

The product of its digits is 691200, while the sum is 48.

The spelling of 51491451648 in words is "fifty-one billion, four hundred ninety-one million, four hundred fifty-one thousand, six hundred forty-eight".