21479873 has 2 divisors, whose sum is σ = 21479874. Its totient is φ = 21479872.

The previous prime is 21479851. The next prime is 21479881. The reversal of 21479873 is 37897412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19998784 + 1481089 = 4472^2 + 1217^2 .

It is a cyclic number.

It is not a de Polignac number, because 21479873 - 2¹⁴ = 21463489 is a prime.

It is a super-2 number, since 2×21479873² = 922769888192258, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21479873.

It is not a weakly prime, because it can be changed into another prime (21479173) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10739936 + 10739937.

It is an arithmetic number, because the mean of its divisors is an integer number (10739937).

Almost surely, 2^21479873 is an apocalyptic number.

It is an amenable number.

21479873 is a deficient number, since it is larger than the sum of its proper divisors (1).

21479873 is an equidigital number, since it uses as much as digits as its factorization.

21479873 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 84672, while the sum is 41.

The square root of 21479873 is about 4634.6383893460. The cubic root of 21479873 is about 277.9780920575.

The spelling of 21479873 in words is "twenty-one million, four hundred seventy-nine thousand, eight hundred seventy-three".