661456811 has 4 divisors (see below), whose sum is σ = 668889000. Its totient is φ = 654024624.

The previous prime is 661456781. The next prime is 661456849. The reversal of 661456811 is 118654166.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661456811 is a prime.

It is a super-2 number, since 2×661456811² = 875050225636579442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661456891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3715961 + ... + 3716138.

It is an arithmetic number, because the mean of its divisors is an integer number (167222250).

Almost surely, 2^661456811 is an apocalyptic number.

661456811 is a deficient number, since it is larger than the sum of its proper divisors (7432189).

661456811 is an equidigital number, since it uses as much as digits as its factorization.

661456811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7432188.

The product of its digits is 34560, while the sum is 38.

The square root of 661456811 is about 25718.8026743081. The cubic root of 661456811 is about 871.2988969879.

The spelling of 661456811 in words is "six hundred sixty-one million, four hundred fifty-six thousand, eight hundred eleven".