61221165642 has 144 divisors (see below), whose sum is σ = 168159595968. Its totient is φ = 15752206080.

The previous prime is 61221165623. The next prime is 61221165659. The reversal of 61221165642 is 24656112216.

61221165642 is a `hidden beast` number, since 6 + 1 + 2 + 2 + 1 + 1 + 6 + 5 + 642 = 666.

It is a super-2 number, since 2×61221165642² (a number of 22 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 61221165597 and 61221165606.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 837993 + ... + 908115.

It is an arithmetic number, because the mean of its divisors is an integer number (1167774972).

Almost surely, 2^61221165642 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61221165642, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (84079797984).

61221165642 is an abundant number, since it is smaller than the sum of its proper divisors (106938430326).

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

61221165642 is a wasteful number, since it uses less digits than its factorization.

61221165642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70205 (or 70189 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

Adding to 61221165642 its reverse (24656112216), we get a palindrome (85877277858).

The spelling of 61221165642 in words is "sixty-one billion, two hundred twenty-one million, one hundred sixty-five thousand, six hundred forty-two".