661002013 has 6 divisors (see below), whose sum is σ = 768920766. Its totient is φ = 566573112.

The previous prime is 661001987. The next prime is 661002019. The reversal of 661002013 is 310200166.

It can be written as a sum of positive squares in only one way, i.e., 512479044 + 148522969 = 22638^2 + 12187^2 .

It is not a de Polignac number, because 661002013 - 2⁹ = 661001501 is a prime.

It is a super-2 number, since 2×661002013² = 873847322380104338, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661002019) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6744870 + ... + 6744967.

It is an arithmetic number, because the mean of its divisors is an integer number (128153461).

Almost surely, 2^661002013 is an apocalyptic number.

It is an amenable number.

661002013 is a deficient number, since it is larger than the sum of its proper divisors (107918753).

661002013 is a wasteful number, since it uses less digits than its factorization.

661002013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13489851 (or 13489844 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 661002013 is about 25709.9594126479. The cubic root of 661002013 is about 871.0991581469.

Adding to 661002013 its reverse (310200166), we get a palindrome (971202179).

The spelling of 661002013 in words is "six hundred sixty-one million, two thousand, thirteen".