61281731628 has 168 divisors, whose sum is σ = 175254785328. Its totient is φ = 18627781248.

The previous prime is 61281731593. The next prime is 61281731639. The reversal of 61281731628 is 82613718216.

61281731628 is a `hidden beast` number, since 6 + 1 + 2 + 8 + 17 + 3 + 1 + 628 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 3136626 + ... + 3156102.

It is an arithmetic number, because the mean of its divisors is an integer number (1043183246).

Almost surely, 2^61281731628 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 61281731628, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87627392664).

61281731628 is an abundant number, since it is smaller than the sum of its proper divisors (113973053700).

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

61281731628 is a wasteful number, since it uses less digits than its factorization.

61281731628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19595 (or 19578 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The spelling of 61281731628 in words is "sixty-one billion, two hundred eighty-one million, seven hundred thirty-one thousand, six hundred twenty-eight".