21802011 has 48 divisors (see below), whose sum is σ = 37537920. Its totient is φ = 11128320.

The previous prime is 21802009. The next prime is 21802051. The reversal of 21802011 is 11020812.

It is not a de Polignac number, because 21802011 - 2¹ = 21802009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21802051) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 156780 + ... + 156918.

It is an arithmetic number, because the mean of its divisors is an integer number (782040).

Almost surely, 2^21802011 is an apocalyptic number.

21802011 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21802011 is a deficient number, since it is larger than the sum of its proper divisors (15735909).

21802011 is a wasteful number, since it uses less digits than its factorization.

21802011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264 (or 257 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

The square root of 21802011 is about 4669.2623614443. The cubic root of 21802011 is about 279.3608337286.

Adding to 21802011 its reverse (11020812), we get a palindrome (32822823).

The spelling of 21802011 in words is "twenty-one million, eight hundred two thousand, eleven".