61644942720 has 384 divisors, whose sum is σ = 222330420000. Its totient is φ = 15718907904.

The previous prime is 61644942703. The next prime is 61644942743. The reversal of 61644942720 is 2724944616.

61644942720 is a `hidden beast` number, since 6 + 164 + 49 + 427 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 17871556 + ... + 17875004.

Almost surely, 2^61644942720 is an apocalyptic number.

61644942720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61644942720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (111165210000).

61644942720 is an abundant number, since it is smaller than the sum of its proper divisors (160685477280).

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

61644942720 is a wasteful number, since it uses less digits than its factorization.

61644942720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3610 (or 3595 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 45.

The spelling of 61644942720 in words is "sixty-one billion, six hundred forty-four million, nine hundred forty-two thousand, seven hundred twenty".