61989 has 4 divisors (see below), whose sum is σ = 82656. Its totient is φ = 41324.

The previous prime is 61987. The next prime is 61991. The reversal of 61989 is 98916.

It is a happy number.

61989 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (61987) and next prime (61991).

It is a cyclic number.

It is not a de Polignac number, because 61989 - 2¹ = 61987 is a prime.

It is a super-2 number, since 2×61989² = 7685272242, which contains 22 as substring.

It is a D-number.

It is a Curzon number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10329 + ... + 10334.

It is an arithmetic number, because the mean of its divisors is an integer number (20664).

2⁶¹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

61989 is a deficient number, since it is larger than the sum of its proper divisors (20667).

61989 is a wasteful number, since it uses less digits than its factorization.

61989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20666.

The product of its digits is 3888, while the sum is 33.

The square root of 61989 is about 248.9759024484. The cubic root of 61989 is about 39.5765752698.

The spelling of 61989 in words is "sixty-one thousand, nine hundred eighty-nine".