13621021 has 4 divisors (see below), whose sum is σ = 13702752. Its totient is φ = 13539292.

The previous prime is 13621019. The next prime is 13621051. The reversal of 13621021 is 12012631.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 13621021 - 2¹ = 13621019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 13620986 and 13621004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13621001) 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, 40615 + ... + 40948.

It is an arithmetic number, because the mean of its divisors is an integer number (3425688).

Almost surely, 2^13621021 is an apocalyptic number.

It is an amenable number.

13621021 is a deficient number, since it is larger than the sum of its proper divisors (81731).

13621021 is an equidigital number, since it uses as much as digits as its factorization.

13621021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81730.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 13621021 is about 3690.6667419316. Note that the first 3 decimals coincide. The cubic root of 13621021 is about 238.8195564997.

Adding to 13621021 its reverse (12012631), we get a palindrome (25633652).

The spelling of 13621021 in words is "thirteen million, six hundred twenty-one thousand, twenty-one".