20721116 has 24 divisors (see below), whose sum is σ = 39530064. Its totient is φ = 9446400.

The previous prime is 20721101. The next prime is 20721131. The reversal of 20721116 is 61112702.

It is an interprime number because it is at equal distance from previous prime (20721101) and next prime (20721131).

It is a congruent number.

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, 1916 + ... + 6716.

It is an arithmetic number, because the mean of its divisors is an integer number (1647086).

Almost surely, 2^20721116 is an apocalyptic number.

20721116 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

20721116 is a deficient number, since it is larger than the sum of its proper divisors (18808948).

20721116 is a wasteful number, since it uses less digits than its factorization.

20721116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4901 (or 4899 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 20.

The square root of 20721116 is about 4552.0452546081. The cubic root of 20721116 is about 274.6656697370.

Adding to 20721116 its reverse (61112702), we get a palindrome (81833818).

The spelling of 20721116 in words is "twenty million, seven hundred twenty-one thousand, one hundred sixteen".