21439307 has 2 divisors, whose sum is σ = 21439308. Its totient is φ = 21439306.

The previous prime is 21439291. The next prime is 21439343. The reversal of 21439307 is 70393412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21439307 - 2⁴ = 21439291 is a prime.

It is a super-3 number, since 3×21439307³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21439307.

It is not a weakly prime, because it can be changed into another prime (21439387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10719653 + 10719654.

It is an arithmetic number, because the mean of its divisors is an integer number (10719654).

Almost surely, 2^21439307 is an apocalyptic number.

21439307 is a deficient number, since it is larger than the sum of its proper divisors (1).

21439307 is an equidigital number, since it uses as much as digits as its factorization.

21439307 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 29.

The square root of 21439307 is about 4630.2599279090. The cubic root of 21439307 is about 277.8029891369.

The spelling of 21439307 in words is "twenty-one million, four hundred thirty-nine thousand, three hundred seven".