861358921720 has 128 divisors (see below), whose sum is σ = 2132919060480. Its totient is φ = 310464000000.

The previous prime is 861358921711. The next prime is 861358921741. The reversal of 861358921720 is 27129853168.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 30747720 + ... + 30775720.

It is an arithmetic number, because the mean of its divisors is an integer number (16663430160).

Almost surely, 2^861358921720 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 861358921720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1066459530240).

861358921720 is an abundant number, since it is smaller than the sum of its proper divisors (1271560138760).

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

861358921720 is a wasteful number, since it uses less digits than its factorization.

861358921720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28637 (or 28633 counting only the distinct ones).

The product of its (nonzero) digits is 1451520, while the sum is 52.

The spelling of 861358921720 in words is "eight hundred sixty-one billion, three hundred fifty-eight million, nine hundred twenty-one thousand, seven hundred twenty".