61491355968 has 672 divisors, whose sum is σ = 208149626880. Its totient is φ = 15924142080.

The previous prime is 61491355927. The next prime is 61491355969. The reversal of 61491355968 is 86955319416.

It is a tau number, because it is divible by the number of its divisors (672).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61491355969) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 597003405 + ... + 597003507.

Almost surely, 2^61491355968 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 61491355968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104074813440).

61491355968 is an abundant number, since it is smaller than the sum of its proper divisors (146658270912).

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

61491355968 is a wasteful number, since it uses less digits than its factorization.

61491355968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275 (or 258 counting only the distinct ones).

The product of its digits is 6998400, while the sum is 57.

The spelling of 61491355968 in words is "sixty-one billion, four hundred ninety-one million, three hundred fifty-five thousand, nine hundred sixty-eight".