21421013 has 4 divisors (see below), whose sum is σ = 21629088. Its totient is φ = 21212940.

The previous prime is 21420991. The next prime is 21421051. The reversal of 21421013 is 31012412.

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 21421013 - 2²² = 17226709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421913) 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, 103883 + ... + 104088.

It is an arithmetic number, because the mean of its divisors is an integer number (5407272).

Almost surely, 2^21421013 is an apocalyptic number.

It is an amenable number.

21421013 is a deficient number, since it is larger than the sum of its proper divisors (208075).

21421013 is a wasteful number, since it uses less digits than its factorization.

21421013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208074.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21421013 is about 4628.2840232639. The cubic root of 21421013 is about 277.7239509155.

Adding to 21421013 its reverse (31012412), we get a palindrome (52433425).

The spelling of 21421013 in words is "twenty-one million, four hundred twenty-one thousand, thirteen".