661211137 has 4 divisors (see below), whose sum is σ = 661417776. Its totient is φ = 661004500.

The previous prime is 661211081. The next prime is 661211179. The reversal of 661211137 is 731112166.

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 a cyclic number.

It is not a de Polignac number, because 661211137 - 2⁷ = 661211009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661211197) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 98443 + ... + 104944.

It is an arithmetic number, because the mean of its divisors is an integer number (165354444).

Almost surely, 2^661211137 is an apocalyptic number.

It is an amenable number.

661211137 is a deficient number, since it is larger than the sum of its proper divisors (206639).

661211137 is a wasteful number, since it uses less digits than its factorization.

661211137 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206638.

The product of its digits is 1512, while the sum is 28.

The square root of 661211137 is about 25714.0260752765. The cubic root of 661211137 is about 871.1910129013.

The spelling of 661211137 in words is "six hundred sixty-one million, two hundred eleven thousand, one hundred thirty-seven".