21026413 has 4 divisors (see below), whose sum is σ = 21038940. Its totient is φ = 21013888.

The previous prime is 21026389. The next prime is 21026419. The reversal of 21026413 is 31462012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7469289 + 13557124 = 2733^2 + 3682^2 .

It is a cyclic number.

It is not a de Polignac number, because 21026413 - 2⁵ = 21026381 is a prime.

It is a super-2 number, since 2×21026413² = 884220087293138, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21026419) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3268 + ... + 7261.

It is an arithmetic number, because the mean of its divisors is an integer number (5259735).

Almost surely, 2^21026413 is an apocalyptic number.

It is an amenable number.

21026413 is a deficient number, since it is larger than the sum of its proper divisors (12527).

21026413 is a wasteful number, since it uses less digits than its factorization.

21026413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12526.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21026413 is about 4585.4566839084. The cubic root of 21026413 is about 276.0080381682.

Adding to 21026413 its reverse (31462012), we get a palindrome (52488425).

It can be divided in two parts, 2102 and 6413, that added together give a triangular number (8515 = T₁₃₀).

The spelling of 21026413 in words is "twenty-one million, twenty-six thousand, four hundred thirteen".