20721107 has 4 divisors (see below), whose sum is σ = 22604856. Its totient is φ = 18837360.

The previous prime is 20721101. The next prime is 20721131. The reversal of 20721107 is 70112702.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20721107 - 2¹⁰ = 20720083 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20721101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 941858 + ... + 941879.

It is an arithmetic number, because the mean of its divisors is an integer number (5651214).

Almost surely, 2^20721107 is an apocalyptic number.

20721107 is a deficient number, since it is larger than the sum of its proper divisors (1883749).

20721107 is a wasteful number, since it uses less digits than its factorization.

20721107 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1883748.

The product of its (nonzero) digits is 196, while the sum is 20.

The square root of 20721107 is about 4552.0442660414. The cubic root of 20721107 is about 274.6656299709.

Adding to 20721107 its reverse (70112702), we get a palindrome (90833809).

It can be divided in two parts, 20 and 721107, that added together give a palindrome (721127).

The spelling of 20721107 in words is "twenty million, seven hundred twenty-one thousand, one hundred seven".