21121443540 has 36 divisors (see below), whose sum is σ = 64068379284. Its totient is φ = 5632384896.

The previous prime is 21121443527. The next prime is 21121443557. The reversal of 21121443540 is 4534412112.

21121443540 is a `hidden beast` number, since 2 + 11 + 214 + 435 + 4 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 9397751364 + 11723692176 = 96942^2 + 108276^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21121443540² (a number of 21 digits) contains 22 as substring.

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, 58670497 + ... + 58670856.

Almost surely, 2^21121443540 is an apocalyptic number.

21121443540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121443540 is an abundant number, since it is smaller than the sum of its proper divisors (42946935744).

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

21121443540 is a wasteful number, since it uses less digits than its factorization.

21121443540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117341368 (or 117341363 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

Adding to 21121443540 its reverse (4534412112), we get a palindrome (25655855652).

The spelling of 21121443540 in words is "twenty-one billion, one hundred twenty-one million, four hundred forty-three thousand, five hundred forty".