21213726 has 32 divisors (see below), whose sum is σ = 43524000. Its totient is φ = 6890880.

The previous prime is 21213719. The next prime is 21213781. The reversal of 21213726 is 62731212.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21213696 and 21213705.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 54340 + ... + 54728.

It is an arithmetic number, because the mean of its divisors is an integer number (1360125).

Almost surely, 2^21213726 is an apocalyptic number.

21213726 is an abundant number, since it is smaller than the sum of its proper divisors (22310274).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21213726 is a wasteful number, since it uses less digits than its factorization.

21213726 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 604.

The product of its digits is 1008, while the sum is 24.

The square root of 21213726 is about 4605.8360804527. The cubic root of 21213726 is about 276.8252187115.

Adding to 21213726 its reverse (62731212), we get a palindrome (83944938).

The spelling of 21213726 in words is "twenty-one million, two hundred thirteen thousand, seven hundred twenty-six".