21520237531 has 8 divisors (see below), whose sum is σ = 23201205104. Its totient is φ = 19842922080.

The previous prime is 21520237513. The next prime is 21520237561. The reversal of 21520237531 is 13573202512.

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

It is a cyclic number.

It is not a de Polignac number, because 21520237531 - 2²¹ = 21518140379 is a prime.

It is a super-2 number, since 2×21520237531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21520237493 and 21520237502.

It is not an unprimeable number, because it can be changed into a prime (21520237561) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 900780 + ... + 924361.

It is an arithmetic number, because the mean of its divisors is an integer number (2900150638).

Almost surely, 2^21520237531 is an apocalyptic number.

21520237531 is a deficient number, since it is larger than the sum of its proper divisors (1680967573).

21520237531 is a wasteful number, since it uses less digits than its factorization.

21520237531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1826061.

The product of its (nonzero) digits is 12600, while the sum is 31.

The spelling of 21520237531 in words is "twenty-one billion, five hundred twenty million, two hundred thirty-seven thousand, five hundred thirty-one".