61531335544 has 128 divisors (see below), whose sum is σ = 136760555520. Its totient is φ = 25409664000.

The previous prime is 61531335487. The next prime is 61531335617. The reversal of 61531335544 is 44553313516.

It is a super-2 number, since 2×61531335544² (a number of 22 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 61531335497 and 61531335506.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 56090004 + ... + 56091100.

It is an arithmetic number, because the mean of its divisors is an integer number (1068441840).

Almost surely, 2^61531335544 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 61531335544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (68380277760).

61531335544 is an abundant number, since it is smaller than the sum of its proper divisors (75229219976).

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

61531335544 is a wasteful number, since it uses less digits than its factorization.

61531335544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1469 (or 1465 counting only the distinct ones).

The product of its digits is 324000, while the sum is 40.

The spelling of 61531335544 in words is "sixty-one billion, five hundred thirty-one million, three hundred thirty-five thousand, five hundred forty-four".