21021011240 has 16 divisors (see below), whose sum is σ = 47297275380. Its totient is φ = 8408404480.

The previous prime is 21021011239. The next prime is 21021011269. The reversal of 21021011240 is 4211012012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17244417124 + 3776594116 = 131318^2 + 61454^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 262762601 + ... + 262762680.

Almost surely, 2^21021011240 is an apocalyptic number.

21021011240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021011240 is an abundant number, since it is smaller than the sum of its proper divisors (26276264140).

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

21021011240 is a wasteful number, since it uses less digits than its factorization.

21021011240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 525525292 (or 525525288 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21021011240 its reverse (4211012012), we get a palindrome (25232023252).

The spelling of 21021011240 in words is "twenty-one billion, twenty-one million, eleven thousand, two hundred forty".