65121640 has 32 divisors (see below), whose sum is σ = 146868480. Its totient is φ = 25987392.

The previous prime is 65121631. The next prime is 65121659. The reversal of 65121640 is 4612156.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17809 + ... + 21151.

It is an arithmetic number, because the mean of its divisors is an integer number (4589640).

Almost surely, 2^65121640 is an apocalyptic number.

It is an amenable number.

65121640 is an abundant number, since it is smaller than the sum of its proper divisors (81746840).

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

65121640 is a wasteful number, since it uses less digits than its factorization.

65121640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3841 (or 3837 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 65121640 is about 8069.7980148204. The cubic root of 65121640 is about 402.3232303778.

Adding to 65121640 its reverse (4612156), we get a palindrome (69733796).

The spelling of 65121640 in words is "sixty-five million, one hundred twenty-one thousand, six hundred forty".