21005309463 has 16 divisors (see below), whose sum is σ = 29660029920. Its totient is φ = 13177368576.

The previous prime is 21005309453. The next prime is 21005309473. The reversal of 21005309463 is 36490350012.

It is an interprime number because it is at equal distance from previous prime (21005309453) and next prime (21005309473).

It is not a de Polignac number, because 21005309463 - 2¹² = 21005305367 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005309443) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 264231 + ... + 334407.

It is an arithmetic number, because the mean of its divisors is an integer number (1853751870).

Almost surely, 2^21005309463 is an apocalyptic number.

21005309463 is a deficient number, since it is larger than the sum of its proper divisors (8654720457).

21005309463 is a wasteful number, since it uses less digits than its factorization.

21005309463 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76066.

The product of its (nonzero) digits is 19440, while the sum is 33.

Adding to 21005309463 its reverse (36490350012), we get a palindrome (57495659475).

The spelling of 21005309463 in words is "twenty-one billion, five million, three hundred nine thousand, four hundred sixty-three".