661511841 has 4 divisors (see below), whose sum is σ = 882015792. Its totient is φ = 441007892.

The previous prime is 661511833. The next prime is 661511849. The reversal of 661511841 is 148115166.

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 an interprime number because it is at equal distance from previous prime (661511833) and next prime (661511849).

It is a cyclic number.

It is not a de Polignac number, because 661511841 - 2³ = 661511833 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661511849) 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, 110251971 + ... + 110251976.

It is an arithmetic number, because the mean of its divisors is an integer number (220503948).

Almost surely, 2^661511841 is an apocalyptic number.

It is an amenable number.

661511841 is a deficient number, since it is larger than the sum of its proper divisors (220503951).

661511841 is a wasteful number, since it uses less digits than its factorization.

661511841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220503950.

The product of its digits is 5760, while the sum is 33.

The square root of 661511841 is about 25719.8724919079. The cubic root of 661511841 is about 871.3230589326.

The spelling of 661511841 in words is "six hundred sixty-one million, five hundred eleven thousand, eight hundred forty-one".