61781665397760 has 4752 divisors, whose sum is σ = 295028433423360. Its totient is φ = 11796468203520.

The previous prime is 61781665397741. The next prime is 61781665397819. The reversal of 61781665397760 is 6779356618716.

61781665397760 is a `hidden beast` number, since 6 + 1 + 7 + 8 + 16 + 6 + 539 + 7 + 76 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 431 ways as a sum of consecutive naturals, for example, 782046397401 + ... + 782046397479.

Almost surely, 2^{61781665397760} is an apocalyptic number.

61781665397760 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 61781665397760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147514216711680).

61781665397760 is an abundant number, since it is smaller than the sum of its proper divisors (233246768025600).

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

61781665397760 is a wasteful number, since it uses less digits than its factorization.

61781665397760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 232 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 480090240, while the sum is 72.

The spelling of 61781665397760 in words is "sixty-one trillion, seven hundred eighty-one billion, six hundred sixty-five million, three hundred ninety-seven thousand, seven hundred sixty".