21654013 has 2 divisors, whose sum is σ = 21654014. Its totient is φ = 21654012.

The previous prime is 21654001. The next prime is 21654019. The reversal of 21654013 is 31045612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20313049 + 1340964 = 4507^2 + 1158^2 .

It is a cyclic number.

It is not a de Polignac number, because 21654013 - 2²¹ = 19556861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21654019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10827006 + 10827007.

It is an arithmetic number, because the mean of its divisors is an integer number (10827007).

Almost surely, 2^21654013 is an apocalyptic number.

It is an amenable number.

21654013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21654013 is an equidigital number, since it uses as much as digits as its factorization.

21654013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21654013 is about 4653.3872609101. The cubic root of 21654013 is about 278.7272721051.

Adding to 21654013 its reverse (31045612), we get a palindrome (52699625).

The spelling of 21654013 in words is "twenty-one million, six hundred fifty-four thousand, thirteen".