64981840 has 180 divisors, whose sum is σ = 194589108. Its totient is φ = 20106240.

The previous prime is 64981817. The next prime is 64981867. The reversal of 64981840 is 4818946.

It can be written as a sum of positive squares in 2 ways, for example, as 30735936 + 34245904 = 5544^2 + 5852^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 64981793 and 64981802.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 474252 + ... + 474388.

Almost surely, 2^64981840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 64981840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97294554).

64981840 is an abundant number, since it is smaller than the sum of its proper divisors (129607268).

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

64981840 is a wasteful number, since it uses less digits than its factorization.

64981840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186 (or 162 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 40.

The square root of 64981840 is about 8061.1314342343. The cubic root of 64981840 is about 402.0351280739.

It can be divided in two parts, 6498 and 1840, that added together give a palindrome (8338).

The spelling of 64981840 in words is "sixty-four million, nine hundred eighty-one thousand, eight hundred forty".