21021020240 has 60 divisors (see below), whose sum is σ = 53720892372. Its totient is φ = 7644003840.

The previous prime is 21021020239. The next prime is 21021020323. The reversal of 21021020240 is 4202012012.

It can be written as a sum of positive squares in 2 ways, for example, as 4092928576 + 16928091664 = 63976^2 + 130108^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1076117 + ... + 1095476.

Almost surely, 2^21021020240 is an apocalyptic number.

21021020240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021020240 is an abundant number, since it is smaller than the sum of its proper divisors (32699872132).

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

21021020240 is a wasteful number, since it uses less digits than its factorization.

21021020240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2171628 (or 2171611 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

Adding to 21021020240 its reverse (4202012012), we get a palindrome (25223032252).

The spelling of 21021020240 in words is "twenty-one billion, twenty-one million, twenty thousand, two hundred forty".