20168721 has 12 divisors (see below), whose sum is σ = 29178240. Its totient is φ = 13424760.

The previous prime is 20168711. The next prime is 20168767. The reversal of 20168721 is 12786102.

It is not a de Polignac number, because 20168721 - 2⁵ = 20168689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20168711) 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, 6216 + ... + 8886.

It is an arithmetic number, because the mean of its divisors is an integer number (2431520).

Almost surely, 2^20168721 is an apocalyptic number.

It is an amenable number.

20168721 is a deficient number, since it is larger than the sum of its proper divisors (9009519).

20168721 is a wasteful number, since it uses less digits than its factorization.

20168721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3516 (or 3513 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 20168721 is about 4490.9599196608. The cubic root of 20168721 is about 272.2029240118.

The spelling of 20168721 in words is "twenty million, one hundred sixty-eight thousand, seven hundred twenty-one".