1601537721 has 32 divisors (see below), whose sum is σ = 2576117760. Its totient is φ = 864556416.

The previous prime is 1601537719. The next prime is 1601537723. The reversal of 1601537721 is 1277351061.

It is an interprime number because it is at equal distance from previous prime (1601537719) and next prime (1601537723).

It is not a de Polignac number, because 1601537721 - 2¹ = 1601537719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1601537723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 140965 + ... + 151901.

It is an arithmetic number, because the mean of its divisors is an integer number (80503680).

Almost surely, 2^1601537721 is an apocalyptic number.

It is an amenable number.

1601537721 is a deficient number, since it is larger than the sum of its proper divisors (974580039).

1601537721 is a wasteful number, since it uses less digits than its factorization.

1601537721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11333.

The product of its (nonzero) digits is 8820, while the sum is 33.

The square root of 1601537721 is about 40019.2168963862. The cubic root of 1601537721 is about 1169.9816689363.

Adding to 1601537721 its reverse (1277351061), we get a palindrome (2878888782).

The spelling of 1601537721 in words is "one billion, six hundred one million, five hundred thirty-seven thousand, seven hundred twenty-one".