21299647 has 2 divisors, whose sum is σ = 21299648. Its totient is φ = 21299646.

The previous prime is 21299639. The next prime is 21299669. The reversal of 21299647 is 74699212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21299647 - 2³ = 21299639 is a prime.

It is a super-3 number, since 3×21299647³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21299687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10649823 + 10649824.

It is an arithmetic number, because the mean of its divisors is an integer number (10649824).

Almost surely, 2^21299647 is an apocalyptic number.

21299647 is a deficient number, since it is larger than the sum of its proper divisors (1).

21299647 is an equidigital number, since it uses as much as digits as its factorization.

21299647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 40.

The square root of 21299647 is about 4615.1540602671. The cubic root of 21299647 is about 277.1984528426.

The spelling of 21299647 in words is "twenty-one million, two hundred ninety-nine thousand, six hundred forty-seven".