561990 has 64 divisors (see below), whose sum is σ = 1596672. Its totient is φ = 124800.

The previous prime is 561983. The next prime is 561997. The reversal of 561990 is 99165.

It is an interprime number because it is at equal distance from previous prime (561983) and next prime (561997).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561997) by changing a digit.

561990 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 31 ways as a sum of consecutive naturals, for example, 4225 + ... + 4355.

It is an arithmetic number, because the mean of its divisors is an integer number (24948).

2⁵⁶¹⁹⁹⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 561990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (798336).

561990 is an abundant number, since it is smaller than the sum of its proper divisors (1034682).

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

561990 is a wasteful number, since it uses less digits than its factorization.

561990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165.

The product of its (nonzero) digits is 2430, while the sum is 30.

The square root of 561990 is about 749.6599228984. The cubic root of 561990 is about 82.5232257840.

It can be divided in two parts, 561 and 990, that added together give a palindrome (1551).

The spelling of 561990 in words is "five hundred sixty-one thousand, nine hundred ninety".