661764263 has 4 divisors (see below), whose sum is σ = 665979480. Its totient is φ = 657549048.

The previous prime is 661764241. The next prime is 661764269. The reversal of 661764263 is 362467166.

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

It is a cyclic number.

It is not a de Polignac number, because 661764263 - 2⁸ = 661764007 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661764263.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661764269) 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, 2107373 + ... + 2107686.

It is an arithmetic number, because the mean of its divisors is an integer number (166494870).

Almost surely, 2^661764263 is an apocalyptic number.

661764263 is a deficient number, since it is larger than the sum of its proper divisors (4215217).

661764263 is a wasteful number, since it uses less digits than its factorization.

661764263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4215216.

The product of its digits is 217728, while the sum is 41.

The square root of 661764263 is about 25724.7791632892. The cubic root of 661764263 is about 871.4338723382.

The spelling of 661764263 in words is "six hundred sixty-one million, seven hundred sixty-four thousand, two hundred sixty-three".