21004000247 has 8 divisors (see below), whose sum is σ = 21320902512. Its totient is φ = 20687198400.

The previous prime is 21004000229. The next prime is 21004000261. The reversal of 21004000247 is 74200040012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21004000247 is a prime.

It is a super-2 number, since 2×21004000247² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004003247) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 469097 + ... + 511917.

It is an arithmetic number, because the mean of its divisors is an integer number (2665112814).

Almost surely, 2^21004000247 is an apocalyptic number.

21004000247 is a deficient number, since it is larger than the sum of its proper divisors (316902265).

21004000247 is an equidigital number, since it uses as much as digits as its factorization.

21004000247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50209.

The product of its (nonzero) digits is 448, while the sum is 20.

Adding to 21004000247 its reverse (74200040012), we get a palindrome (95204040259).

The spelling of 21004000247 in words is "twenty-one billion, four million, two hundred forty-seven", and thus it is an aban number.