61819779840 has 864 divisors, whose sum is σ = 250538803200. Its totient is φ = 12875563008.

The previous prime is 61819779821. The next prime is 61819779841. The reversal of 61819779840 is 4897791816.

It is a Harshad number since it is a multiple of its sum of digits (60).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61819779841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 310652061 + ... + 310652259.

Almost surely, 2^61819779840 is an apocalyptic number.

61819779840 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 61819779840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (125269401600).

61819779840 is an abundant number, since it is smaller than the sum of its proper divisors (188719023360).

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

61819779840 is a wasteful number, since it uses less digits than its factorization.

61819779840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 377 (or 356 counting only the distinct ones).

The product of its (nonzero) digits is 6096384, while the sum is 60.

The spelling of 61819779840 in words is "sixty-one billion, eight hundred nineteen million, seven hundred seventy-nine thousand, eight hundred forty".