661959 has 8 divisors (see below), whose sum is σ = 980720. Its totient is φ = 441288.

The previous prime is 661951. The next prime is 661961. The reversal of 661959 is 959166.

661959 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661959 - 2³ = 661951 is a prime.

It is a Duffinian number.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661951) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12232 + ... + 12285.

It is an arithmetic number, because the mean of its divisors is an integer number (122590).

2⁶⁶¹⁹⁵⁹ is an apocalyptic number.

661959 is a deficient number, since it is larger than the sum of its proper divisors (318761).

661959 is a wasteful number, since it uses less digits than its factorization.

661959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24526 (or 24520 counting only the distinct ones).

The product of its digits is 14580, while the sum is 36.

The square root of 661959 is about 813.6086282728. The cubic root of 661959 is about 87.1519342741.

It can be divided in two parts, 66 and 1959, that added together give a square (2025 = 45²).

The spelling of 661959 in words is "six hundred sixty-one thousand, nine hundred fifty-nine".