20071821 has 24 divisors (see below), whose sum is σ = 33964704. Its totient is φ = 10426080.

The previous prime is 20071819. The next prime is 20071829. The reversal of 20071821 is 12817002.

It is not a de Polignac number, because 20071821 - 2¹ = 20071819 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20071829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4590 + ... + 7823.

It is an arithmetic number, because the mean of its divisors is an integer number (1415196).

Almost surely, 2^20071821 is an apocalyptic number.

20071821 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20071821 is a deficient number, since it is larger than the sum of its proper divisors (13892883).

20071821 is a wasteful number, since it uses less digits than its factorization.

20071821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12441 (or 12434 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 20071821 is about 4480.1585909430. The cubic root of 20071821 is about 271.7662938113.

Adding to 20071821 its reverse (12817002), we get a palindrome (32888823).

It can be divided in two parts, 2007 and 1821, that added together give a triangular number (3828 = T₈₇).

The spelling of 20071821 in words is "twenty million, seventy-one thousand, eight hundred twenty-one".