20211381 has 12 divisors (see below), whose sum is σ = 29479008. Its totient is φ = 13342824.

The previous prime is 20211379. The next prime is 20211407. The reversal of 20211381 is 18311202.

It is not a de Polignac number, because 20211381 - 2¹ = 20211379 is a prime.

It is a super-2 number, since 2×20211381² = 816999843854322, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20211481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9975 + ... + 11828.

It is an arithmetic number, because the mean of its divisors is an integer number (2456584).

Almost surely, 2^20211381 is an apocalyptic number.

It is an amenable number.

20211381 is a deficient number, since it is larger than the sum of its proper divisors (9267627).

20211381 is a wasteful number, since it uses less digits than its factorization.

20211381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21912 (or 21909 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 20211381 is about 4495.7069521934. The cubic root of 20211381 is about 272.3947061143.

Adding to 20211381 its reverse (18311202), we get a palindrome (38522583).

The spelling of 20211381 in words is "twenty million, two hundred eleven thousand, three hundred eighty-one".