61644291840 has 180 divisors, whose sum is σ = 220574920104. Its totient is φ = 16438450176.

The previous prime is 61644291829. The next prime is 61644291851. The reversal of 61644291840 is 4819244616.

61644291840 is a `hidden beast` number, since 616 + 4 + 4 + 29 + 1 + 8 + 4 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (61644291829) and next prime (61644291851).

It is a tau number, because it is divible by the number of its divisors (180).

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 19 ways as a sum of consecutive naturals, for example, 193602 + ... + 400961.

Almost surely, 2^61644291840 is an apocalyptic number.

61644291840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

61644291840 is an abundant number, since it is smaller than the sum of its proper divisors (158930628264).

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

61644291840 is an equidigital number, since it uses as much as digits as its factorization.

61644291840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 594596 (or 594573 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 45.

The spelling of 61644291840 in words is "sixty-one billion, six hundred forty-four million, two hundred ninety-one thousand, eight hundred forty".