63730721661 has 16 divisors (see below), whose sum is σ = 87904911360. Its totient is φ = 41027762160.

The previous prime is 63730721651. The next prime is 63730721683. The reversal of 63730721661 is 16612703736.

It is a happy number.

It is not a de Polignac number, because 63730721661 - 2⁹ = 63730721149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (63730721651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 696981 + ... + 783098.

It is an arithmetic number, because the mean of its divisors is an integer number (5494056960).

Almost surely, 2^63730721661 is an apocalyptic number.

It is an amenable number.

63730721661 is a deficient number, since it is larger than the sum of its proper divisors (24174189699).

63730721661 is a wasteful number, since it uses less digits than its factorization.

63730721661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1480576.

The product of its (nonzero) digits is 190512, while the sum is 42.

The spelling of 63730721661 in words is "sixty-three billion, seven hundred thirty million, seven hundred twenty-one thousand, six hundred sixty-one".