64161721 has 16 divisors (see below), whose sum is σ = 71092224. Its totient is φ = 57536064.

The previous prime is 64161709. The next prime is 64161781. The reversal of 64161721 is 12716146.

It is a cyclic number.

It is not a de Polignac number, because 64161721 - 2²⁵ = 30607289 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 64161721.

It is not an unprimeable number, because it can be changed into a prime (64161781) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 105400 + ... + 106006.

It is an arithmetic number, because the mean of its divisors is an integer number (4443264).

Almost surely, 2^64161721 is an apocalyptic number.

It is an amenable number.

64161721 is a deficient number, since it is larger than the sum of its proper divisors (6930503).

64161721 is a wasteful number, since it uses less digits than its factorization.

64161721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 840.

The product of its digits is 2016, while the sum is 28.

The square root of 64161721 is about 8010.1011853784. The cubic root of 64161721 is about 400.3366353621.

Adding to 64161721 its reverse (12716146), we get a palindrome (76877867).

The spelling of 64161721 in words is "sixty-four million, one hundred sixty-one thousand, seven hundred twenty-one".