61281720513 has 96 divisors (see below), whose sum is σ = 107775892224. Its totient is φ = 33159684096.

The previous prime is 61281720497. The next prime is 61281720523. The reversal of 61281720513 is 31502718216.

61281720513 is a `hidden beast` number, since 6 + 128 + 17 + 2 + 0 + 513 = 666.

It is not a de Polignac number, because 61281720513 - 2⁴ = 61281720497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (61281720523) 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, 1951545 + ... + 1982697.

It is an arithmetic number, because the mean of its divisors is an integer number (1122665544).

Almost surely, 2^61281720513 is an apocalyptic number.

It is an amenable number.

61281720513 is a deficient number, since it is larger than the sum of its proper divisors (46494171711).

61281720513 is a wasteful number, since it uses less digits than its factorization.

61281720513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31255 (or 31252 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The spelling of 61281720513 in words is "sixty-one billion, two hundred eighty-one million, seven hundred twenty thousand, five hundred thirteen".