21520734537031 has 4 divisors (see below), whose sum is σ = 21978622505952. Its totient is φ = 21062846568112.

The previous prime is 21520734536989. The next prime is 21520734537077. The reversal of 21520734537031 is 13073543702512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21520734537031 - 2²⁷ = 21520600319303 is a prime.

It is a super-2 number, since 2×21520734537031² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520734537331) 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, 228943984390 + ... + 228943984483.

It is an arithmetic number, because the mean of its divisors is an integer number (5494655626488).

Almost surely, 2^{21520734537031} is an apocalyptic number.

21520734537031 is a deficient number, since it is larger than the sum of its proper divisors (457887968921).

21520734537031 is an equidigital number, since it uses as much as digits as its factorization.

21520734537031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 457887968920.

The product of its (nonzero) digits is 529200, while the sum is 43.

The spelling of 21520734537031 in words is "twenty-one trillion, five hundred twenty billion, seven hundred thirty-four million, five hundred thirty-seven thousand, thirty-one".