21510344420 has 24 divisors (see below), whose sum is σ = 46392582264. Its totient is φ = 8371593216.

The previous prime is 21510344419. The next prime is 21510344447. The reversal of 21510344420 is 2444301512.

It can be written as a sum of positive squares in 4 ways, for example, as 2109197476 + 19401146944 = 45926^2 + 139288^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21510344420.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14533277 + ... + 14534756.

It is an arithmetic number, because the mean of its divisors is an integer number (1933024261).

Almost surely, 2^21510344420 is an apocalyptic number.

21510344420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21510344420 is an abundant number, since it is smaller than the sum of its proper divisors (24882237844).

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

21510344420 is a wasteful number, since it uses less digits than its factorization.

21510344420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29068079 (or 29068077 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 26.

Adding to 21510344420 its reverse (2444301512), we get a palindrome (23954645932).

The spelling of 21510344420 in words is "twenty-one billion, five hundred ten million, three hundred forty-four thousand, four hundred twenty".