21121506537 has 32 divisors (see below), whose sum is σ = 30021425280. Its totient is φ = 13162859520.

The previous prime is 21121506521. The next prime is 21121506557. The reversal of 21121506537 is 73560512112.

It is not a de Polignac number, because 21121506537 - 2⁴ = 21121506521 is a prime.

It is a super-2 number, since 2×21121506537² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121506498 and 21121506507.

It is not an unprimeable number, because it can be changed into a prime (21121506557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5382058 + ... + 5385980.

It is an arithmetic number, because the mean of its divisors is an integer number (938169540).

Almost surely, 2^21121506537 is an apocalyptic number.

It is an amenable number.

21121506537 is a deficient number, since it is larger than the sum of its proper divisors (8899918743).

21121506537 is a wasteful number, since it uses less digits than its factorization.

21121506537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4633.

The product of its (nonzero) digits is 12600, while the sum is 33.

The spelling of 21121506537 in words is "twenty-one billion, one hundred twenty-one million, five hundred six thousand, five hundred thirty-seven".