1001660721 has 8 divisors (see below), whose sum is σ = 1339761984. Its totient is φ = 665666640.

The previous prime is 1001660713. The next prime is 1001660767. The reversal of 1001660721 is 1270661001.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1001660721 - 2³ = 1001660713 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1001660691 and 1001660700.

It is not an unprimeable number, because it can be changed into a prime (1001660771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 525685 + ... + 527586.

It is an arithmetic number, because the mean of its divisors is an integer number (167470248).

Almost surely, 2^1001660721 is an apocalyptic number.

It is an amenable number.

1001660721 is a deficient number, since it is larger than the sum of its proper divisors (338101263).

1001660721 is a wasteful number, since it uses less digits than its factorization.

1001660721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1053591.

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 1001660721 is about 31649.0240133878. The cubic root of 1001660721 is about 1000.5532675053.

The spelling of 1001660721 in words is "one billion, one million, six hundred sixty thousand, seven hundred twenty-one".