661764270 has 64 divisors (see below), whose sum is σ = 1689180480. Its totient is φ = 165347328.

The previous prime is 661764269. The next prime is 661764283. The reversal of 661764270 is 72467166.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 116046 + ... + 121614.

It is an arithmetic number, because the mean of its divisors is an integer number (26393445).

Almost surely, 2^661764270 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661764270, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (844590240).

661764270 is an abundant number, since it is smaller than the sum of its proper divisors (1027416210).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661764270 is a wasteful number, since it uses less digits than its factorization.

661764270 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5829.

The product of its (nonzero) digits is 84672, while the sum is 39.

The square root of 661764270 is about 25724.7792993448. The cubic root of 661764270 is about 871.4338754108.

The spelling of 661764270 in words is "six hundred sixty-one million, seven hundred sixty-four thousand, two hundred seventy".