661956 has 12 divisors (see below), whose sum is σ = 1544592. Its totient is φ = 220648.

The previous prime is 661951. The next prime is 661961. The reversal of 661956 is 659166.

661956 = T₉₈ + T₉₉ + ... + T₁₆₉.

661956 = 13⁴ + 14⁴ + ... + 20⁴.

It is an interprime number because it is at equal distance from previous prime (661951) and next prime (661961).

It is a tau number, because it is divible by the number of its divisors (12).

It is a plaindrome in base 14.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 661956.

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

661956 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27570 + ... + 27593.

It is an arithmetic number, because the mean of its divisors is an integer number (128716).

2⁶⁶¹⁹⁵⁶ is an apocalyptic number.

It is an amenable number.

661956 is an abundant number, since it is smaller than the sum of its proper divisors (882636).

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

661956 is a wasteful number, since it uses less digits than its factorization.

661956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55170 (or 55168 counting only the distinct ones).

The product of its digits is 9720, while the sum is 33.

The square root of 661956 is about 813.6067846325. The cubic root of 661956 is about 87.1518026163.

The spelling of 661956 in words is "six hundred sixty-one thousand, nine hundred fifty-six".