21436873 has 2 divisors, whose sum is σ = 21436874. Its totient is φ = 21436872.

The previous prime is 21436871. The next prime is 21436927. The reversal of 21436873 is 37863412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16224784 + 5212089 = 4028^2 + 2283^2 .

It is a cyclic number.

It is not a de Polignac number, because 21436873 - 2¹ = 21436871 is a prime.

Together with 21436871, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21436871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10718436 + 10718437.

It is an arithmetic number, because the mean of its divisors is an integer number (10718437).

Almost surely, 2^21436873 is an apocalyptic number.

It is an amenable number.

21436873 is a deficient number, since it is larger than the sum of its proper divisors (1).

21436873 is an equidigital number, since it uses as much as digits as its factorization.

21436873 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 34.

The square root of 21436873 is about 4629.9970842323. The cubic root of 21436873 is about 277.7924757675.

The spelling of 21436873 in words is "twenty-one million, four hundred thirty-six thousand, eight hundred seventy-three".