611664821 has 4 divisors (see below), whose sum is σ = 612077100. Its totient is φ = 611252544.

The previous prime is 611664793. The next prime is 611664827. The reversal of 611664821 is 128466116.

611664821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 316306225 + 295358596 = 17785^2 + 17186^2 .

It is a cyclic number.

It is not a de Polignac number, because 611664821 - 2²² = 607470517 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (611664827) 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, 203906 + ... + 206883.

It is an arithmetic number, because the mean of its divisors is an integer number (153019275).

Almost surely, 2^611664821 is an apocalyptic number.

It is an amenable number.

611664821 is a deficient number, since it is larger than the sum of its proper divisors (412279).

611664821 is a wasteful number, since it uses less digits than its factorization.

611664821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412278.

The product of its digits is 13824, while the sum is 35.

The square root of 611664821 is about 24731.8584218817. The cubic root of 611664821 is about 848.8634502966.

The spelling of 611664821 in words is "six hundred eleven million, six hundred sixty-four thousand, eight hundred twenty-one".