1000643720 has 16 divisors (see below), whose sum is σ = 2251448460. Its totient is φ = 400257472.

The previous prime is 1000643713. The next prime is 1000643723. The reversal of 1000643720 is 273460001.

It can be written as a sum of positive squares in 2 ways, for example, as 941630596 + 59013124 = 30686^2 + 7682^2 .

It is not an unprimeable number, because it can be changed into a prime (1000643723) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12508007 + ... + 12508086.

Almost surely, 2^1000643720 is an apocalyptic number.

1000643720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1000643720 is an abundant number, since it is smaller than the sum of its proper divisors (1250804740).

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

1000643720 is a wasteful number, since it uses less digits than its factorization.

1000643720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25016104 (or 25016100 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 23.

The square root of 1000643720 is about 31632.9530711251. The cubic root of 1000643720 is about 1000.2145273081.

The spelling of 1000643720 in words is "one billion, six hundred forty-three thousand, seven hundred twenty".