64408981 has 12 divisors (see below), whose sum is σ = 80688972. Its totient is φ = 50960448.

The previous prime is 64408973. The next prime is 64408987. The reversal of 64408981 is 18980446.

It can be written as a sum of positive squares in 2 ways, for example, as 4036081 + 60372900 = 2009^2 + 7770^2 .

It is not a de Polignac number, because 64408981 - 2³ = 64408973 is a prime.

It is a super-2 number, since 2×64408981² = 8297033666916722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64408987) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 49920 + ... + 51193.

It is an arithmetic number, because the mean of its divisors is an integer number (6724081).

Almost surely, 2^64408981 is an apocalyptic number.

It is an amenable number.

64408981 is a deficient number, since it is larger than the sum of its proper divisors (16279991).

64408981 is a wasteful number, since it uses less digits than its factorization.

64408981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101140 (or 101133 counting only the distinct ones).

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

The square root of 64408981 is about 8025.5206061663. The cubic root of 64408981 is about 400.8502352197.

The spelling of 64408981 in words is "sixty-four million, four hundred eight thousand, nine hundred eighty-one".