65439990 has 288 divisors, whose sum is σ = 230480640. Its totient is φ = 12700800.

The previous prime is 65439961. The next prime is 65440031. The reversal of 65439990 is 9993456.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 921655 + ... + 921725.

It is an arithmetic number, because the mean of its divisors is an integer number (800280).

Almost surely, 2^65439990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 65439990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115240320).

65439990 is an abundant number, since it is smaller than the sum of its proper divisors (165040650).

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

65439990 is a wasteful number, since it uses less digits than its factorization.

65439990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128 (or 118 counting only the distinct ones).

The product of its (nonzero) digits is 262440, while the sum is 45.

The square root of 65439990 is about 8089.4987483774. The cubic root of 65439990 is about 402.9777565731.

The spelling of 65439990 in words is "sixty-five million, four hundred thirty-nine thousand, nine hundred ninety".