21709433 has 2 divisors, whose sum is σ = 21709434. Its totient is φ = 21709432.

The previous prime is 21709411. The next prime is 21709439. The reversal of 21709433 is 33490712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21409129 + 300304 = 4627^2 + 548^2 .

It is a cyclic number.

It is not a de Polignac number, because 21709433 - 2¹² = 21705337 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21709396 and 21709405.

It is not a weakly prime, because it can be changed into another prime (21709439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10854716 + 10854717.

It is an arithmetic number, because the mean of its divisors is an integer number (10854717).

Almost surely, 2^21709433 is an apocalyptic number.

It is an amenable number.

21709433 is a deficient number, since it is larger than the sum of its proper divisors (1).

21709433 is an equidigital number, since it uses as much as digits as its factorization.

21709433 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 21709433 is about 4659.3382577357. The cubic root of 21709433 is about 278.9648555656.

The spelling of 21709433 in words is "twenty-one million, seven hundred nine thousand, four hundred thirty-three".