661813570 has 32 divisors (see below), whose sum is σ = 1376009856. Its totient is φ = 226502400.

The previous prime is 661813549. The next prime is 661813571. The reversal of 661813570 is 75318166.

661813570 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×661813570² = 875994402872289800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661813571) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 175086 + ... + 178825.

It is an arithmetic number, because the mean of its divisors is an integer number (43000308).

Almost surely, 2^661813570 is an apocalyptic number.

661813570 is an abundant number, since it is smaller than the sum of its proper divisors (714196286).

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

661813570 is a wasteful number, since it uses less digits than its factorization.

661813570 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 353946.

The product of its (nonzero) digits is 30240, while the sum is 37.

The square root of 661813570 is about 25725.7375015761. The cubic root of 661813570 is about 871.4555148501.

It can be divided in two parts, 66181 and 3570, that added together give a triangular number (69751 = T₃₇₃).

The spelling of 661813570 in words is "six hundred sixty-one million, eight hundred thirteen thousand, five hundred seventy".