61644780400 has 240 divisors, whose sum is σ = 171853000704. Its totient is φ = 20813783040.

The previous prime is 61644780397. The next prime is 61644780403. The reversal of 61644780400 is 408744616.

It is an interprime number because it is at equal distance from previous prime (61644780397) and next prime (61644780403).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61644780403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 71430369 + ... + 71431231.

Almost surely, 2^61644780400 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 61644780400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (85926500352).

61644780400 is an abundant number, since it is smaller than the sum of its proper divisors (110208220304).

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

61644780400 is a wasteful number, since it uses less digits than its factorization.

61644780400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1248 (or 1237 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 40.

The spelling of 61644780400 in words is "sixty-one billion, six hundred forty-four million, seven hundred eighty thousand, four hundred".