1501001661 has 4 divisors (see below), whose sum is σ = 2001335552. Its totient is φ = 1000667772.

The previous prime is 1501001641. The next prime is 1501001669. The reversal of 1501001661 is 1661001051.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1501001661 - 2¹⁰ = 1501000637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1501001669) 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, 250166941 + ... + 250166946.

It is an arithmetic number, because the mean of its divisors is an integer number (500333888).

Almost surely, 2^1501001661 is an apocalyptic number.

It is an amenable number.

1501001661 is a deficient number, since it is larger than the sum of its proper divisors (500333891).

1501001661 is an equidigital number, since it uses as much as digits as its factorization.

1501001661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 500333890.

The product of its (nonzero) digits is 180, while the sum is 21.

The square root of 1501001661 is about 38742.7626918887. The cubic root of 1501001661 is about 1144.9689893269.

The spelling of 1501001661 in words is "one billion, five hundred one million, one thousand, six hundred sixty-one".