661001001511 has 4 divisors (see below), whose sum is σ = 661011545512. Its totient is φ = 660990457512.

The previous prime is 661001001503. The next prime is 661001001523. The reversal of 661001001511 is 115100100166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661001001511 - 2³ = 661001001503 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 (661001001811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5177400 + ... + 5303533.

It is an arithmetic number, because the mean of its divisors is an integer number (165252886378).

Almost surely, 2^661001001511 is an apocalyptic number.

661001001511 is a deficient number, since it is larger than the sum of its proper divisors (10544001).

661001001511 is a wasteful number, since it uses less digits than its factorization.

661001001511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10544000.

The product of its (nonzero) digits is 180, while the sum is 22.

Adding to 661001001511 its reverse (115100100166), we get a palindrome (776101101677).

The spelling of 661001001511 in words is "six hundred sixty-one billion, one million, one thousand, five hundred eleven".