21403505215 has 4 divisors (see below), whose sum is σ = 25684206264. Its totient is φ = 17122804168.

The previous prime is 21403505161. The next prime is 21403505219. The reversal of 21403505215 is 51250530412.

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 21403505215 - 2¹⁷ = 21403374143 is a prime.

It is a super-2 number, since 2×21403505215² (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 (21403505219) 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, 2140350517 + ... + 2140350526.

It is an arithmetic number, because the mean of its divisors is an integer number (6421051566).

Almost surely, 2^21403505215 is an apocalyptic number.

21403505215 is a deficient number, since it is larger than the sum of its proper divisors (4280701049).

21403505215 is an equidigital number, since it uses as much as digits as its factorization.

21403505215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4280701048.

The product of its (nonzero) digits is 6000, while the sum is 28.

The spelling of 21403505215 in words is "twenty-one billion, four hundred three million, five hundred five thousand, two hundred fifteen".