661997633 has 4 divisors (see below), whose sum is σ = 722179248. Its totient is φ = 601816020.

The previous prime is 661997621. The next prime is 661997659. The reversal of 661997633 is 336799166.

It is a happy number.

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 661997633 - 2¹⁴ = 661981249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661997933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30090791 + ... + 30090812.

It is an arithmetic number, because the mean of its divisors is an integer number (180544812).

Almost surely, 2^661997633 is an apocalyptic number.

It is an amenable number.

661997633 is a deficient number, since it is larger than the sum of its proper divisors (60181615).

661997633 is a wasteful number, since it uses less digits than its factorization.

661997633 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60181614.

The product of its digits is 1102248, while the sum is 50.

The square root of 661997633 is about 25729.3146624623. The cubic root of 661997633 is about 871.5362968385.

The spelling of 661997633 in words is "six hundred sixty-one million, nine hundred ninety-seven thousand, six hundred thirty-three".