21372111 has 24 divisors (see below), whose sum is σ = 33493824. Its totient is φ = 13079040.

The previous prime is 21372103. The next prime is 21372133. The reversal of 21372111 is 11127312.

It is a happy number.

It is not a de Polignac number, because 21372111 - 2³ = 21372103 is a prime.

It is a super-3 number, since 3×21372111³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21372151) 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 23 ways as a sum of consecutive naturals, for example, 4570 + ... + 7976.

It is an arithmetic number, because the mean of its divisors is an integer number (1395576).

Almost surely, 2^21372111 is an apocalyptic number.

21372111 is a deficient number, since it is larger than the sum of its proper divisors (12121713).

21372111 is a wasteful number, since it uses less digits than its factorization.

21372111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3471 (or 3468 counting only the distinct ones).

The product of its digits is 84, while the sum is 18.

The square root of 21372111 is about 4622.9980532118. The cubic root of 21372111 is about 277.5124513527.

Adding to 21372111 its sum of digits (18), we get a square (21372129 = 4623²).

Adding to 21372111 its reverse (11127312), we get a palindrome (32499423).

The spelling of 21372111 in words is "twenty-one million, three hundred seventy-two thousand, one hundred eleven".