64780981 has 4 divisors (see below), whose sum is σ = 64809612. Its totient is φ = 64752352.

The previous prime is 64780973. The next prime is 64781011. The reversal of 64780981 is 18908746.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18908746 = 2 ⋅9454373.

It can be written as a sum of positive squares in 2 ways, for example, as 19096900 + 45684081 = 4370^2 + 6759^2 .

It is a cyclic number.

It is not a de Polignac number, because 64780981 - 2³ = 64780973 is a prime.

It is a super-2 number, since 2×64780981² = 8393150998644722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64780921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10600 + ... + 15553.

It is an arithmetic number, because the mean of its divisors is an integer number (16202403).

Almost surely, 2^64780981 is an apocalyptic number.

It is an amenable number.

64780981 is a deficient number, since it is larger than the sum of its proper divisors (28631).

64780981 is a wasteful number, since it uses less digits than its factorization.

64780981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28630.

The product of its (nonzero) digits is 96768, while the sum is 43.

The square root of 64780981 is about 8048.6633051706. The cubic root of 64780981 is about 401.6204700768.

The spelling of 64780981 in words is "sixty-four million, seven hundred eighty thousand, nine hundred eighty-one".