6445161720 has 192 divisors, whose sum is σ = 22779169920. Its totient is φ = 1573834752.

The previous prime is 6445161713. The next prime is 6445161739. The reversal of 6445161720 is 271615446.

6445161720 is a `hidden beast` number, since 644 + 5 + 1 + 6 + 1 + 7 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 212209 + ... + 240671.

It is an arithmetic number, because the mean of its divisors is an integer number (118641510).

Almost surely, 2^6445161720 is an apocalyptic number.

6445161720 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 6445161720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11389584960).

6445161720 is an abundant number, since it is smaller than the sum of its proper divisors (16334008200).

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

6445161720 is a wasteful number, since it uses less digits than its factorization.

6445161720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28534 (or 28527 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 6445161720 is about 80281.7645545986. The cubic root of 6445161720 is about 1860.9924291049.

The spelling of 6445161720 in words is "six billion, four hundred forty-five million, one hundred sixty-one thousand, seven hundred twenty".