21505410007 has 4 divisors (see below), whose sum is σ = 21514399200. Its totient is φ = 21496420816.

The previous prime is 21505409971. The next prime is 21505410049. The reversal of 21505410007 is 70001450512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21505410007 - 2¹⁵ = 21505377239 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21505410097) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4491007 + ... + 4495792.

It is an arithmetic number, because the mean of its divisors is an integer number (5378599800).

Almost surely, 2^21505410007 is an apocalyptic number.

21505410007 is a deficient number, since it is larger than the sum of its proper divisors (8989193).

21505410007 is an equidigital number, since it uses as much as digits as its factorization.

21505410007 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8989192.

The product of its (nonzero) digits is 1400, while the sum is 25.

Adding to 21505410007 its reverse (70001450512), we get a palindrome (91506860519).

The spelling of 21505410007 in words is "twenty-one billion, five hundred five million, four hundred ten thousand, seven".