21450571640 has 16 divisors (see below), whose sum is σ = 48263786280. Its totient is φ = 8580228640.

The previous prime is 21450571619. The next prime is 21450571643. The reversal of 21450571640 is 4617505412.

It is a self number, because there is not a number n which added to its sum of digits gives 21450571640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21450571643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 268132106 + ... + 268132185.

Almost surely, 2^21450571640 is an apocalyptic number.

21450571640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21450571640 is an abundant number, since it is smaller than the sum of its proper divisors (26813214640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21450571640 is a wasteful number, since it uses less digits than its factorization.

21450571640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 536264302 (or 536264298 counting only the distinct ones).

The product of its (nonzero) digits is 33600, while the sum is 35.

The spelling of 21450571640 in words is "twenty-one billion, four hundred fifty million, five hundred seventy-one thousand, six hundred forty".