661390 has 24 divisors (see below), whose sum is σ = 1274760. Its totient is φ = 246384.

The previous prime is 661373. The next prime is 661393. The reversal of 661390 is 93166.

661390 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661393) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11181 + ... + 11239.

It is an arithmetic number, because the mean of its divisors is an integer number (53115).

2⁶⁶¹³⁹⁰ is an apocalyptic number.

661390 is a deficient number, since it is larger than the sum of its proper divisors (613370).

661390 is a wasteful number, since it uses less digits than its factorization.

661390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144 (or 85 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 661390 is about 813.2588763733. The cubic root of 661390 is about 87.1269560575.

The spelling of 661390 in words is "six hundred sixty-one thousand, three hundred ninety".