21008215473 has 8 divisors (see below), whose sum is σ = 32012518848. Its totient is φ = 12004694544.

The previous prime is 21008215447. The next prime is 21008215483. The reversal of 21008215473 is 37451280012.

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

It is not a de Polignac number, because 21008215473 - 2¹³ = 21008207281 is a prime.

It is a super-2 number, since 2×21008215473² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21008215483) 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, 500195586 + ... + 500195627.

It is an arithmetic number, because the mean of its divisors is an integer number (4001564856).

Almost surely, 2^21008215473 is an apocalyptic number.

It is an amenable number.

21008215473 is a deficient number, since it is larger than the sum of its proper divisors (11004303375).

21008215473 is a wasteful number, since it uses less digits than its factorization.

21008215473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1000391223.

The product of its (nonzero) digits is 13440, while the sum is 33.

Adding to 21008215473 its reverse (37451280012), we get a palindrome (58459495485).

The spelling of 21008215473 in words is "twenty-one billion, eight million, two hundred fifteen thousand, four hundred seventy-three".