21121534538 has 8 divisors (see below), whose sum is σ = 34119401988. Its totient is φ = 9748400544.

The previous prime is 21121534537. The next prime is 21121534543. The reversal of 21121534538 is 83543512112.

It can be written as a sum of positive squares in 2 ways, for example, as 21035731369 + 85803169 = 145037^2 + 9263^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21121534538² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121534498 and 21121534507.

It is not an unprimeable number, because it can be changed into a prime (21121534537) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 406183331 + ... + 406183382.

Almost surely, 2^21121534538 is an apocalyptic number.

21121534538 is a deficient number, since it is larger than the sum of its proper divisors (12997867450).

21121534538 is a wasteful number, since it uses less digits than its factorization.

21121534538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 812366728.

The product of its digits is 28800, while the sum is 35.

The spelling of 21121534538 in words is "twenty-one billion, one hundred twenty-one million, five hundred thirty-four thousand, five hundred thirty-eight".