21205014720 has 56 divisors (see below), whose sum is σ = 67325924784. Its totient is φ = 5654670336.

The previous prime is 21205014707. The next prime is 21205014731. The reversal of 21205014720 is 2741050212.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11043319 + ... + 11045238.

Almost surely, 2^21205014720 is an apocalyptic number.

21205014720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21205014720 is an abundant number, since it is smaller than the sum of its proper divisors (46120910064).

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

21205014720 is a wasteful number, since it uses less digits than its factorization.

21205014720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22088577 (or 22088567 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 24.

Adding to 21205014720 its reverse (2741050212), we get a palindrome (23946064932).

The spelling of 21205014720 in words is "twenty-one billion, two hundred five million, fourteen thousand, seven hundred twenty".