1720721001 has 32 divisors (see below), whose sum is σ = 2431316608. Its totient is φ = 1081175040.

The previous prime is 1720720957. The next prime is 1720721027. The reversal of 1720721001 is 1001270271.

It is a happy number.

It is not a de Polignac number, because 1720721001 - 2¹⁴ = 1720704617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1720721201) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 451761 + ... + 455553.

It is an arithmetic number, because the mean of its divisors is an integer number (75978644).

Almost surely, 2^1720721001 is an apocalyptic number.

It is an amenable number.

1720721001 is a deficient number, since it is larger than the sum of its proper divisors (710595607).

1720721001 is a wasteful number, since it uses less digits than its factorization.

1720721001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3961.

The product of its (nonzero) digits is 196, while the sum is 21.

The square root of 1720721001 is about 41481.5742348335. The cubic root of 1720721001 is about 1198.3126750853.

Adding to 1720721001 its reverse (1001270271), we get a palindrome (2721991272).

The spelling of 1720721001 in words is "one billion, seven hundred twenty million, seven hundred twenty-one thousand, one".