21520000431251 has 8 divisors (see below), whose sum is σ = 24594333848064. Its totient is φ = 18445678924680.

The previous prime is 21520000431227. The next prime is 21520000431257. The reversal of 21520000431251 is 15213400002512.

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

It is a de Polignac number, because none of the positive numbers 2^k-21520000431251 is a prime.

It is a super-2 number, since 2×21520000431251² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21520000431251.

It is not an unprimeable number, because it can be changed into a prime (21520000431257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1304876 + ... + 6688998.

It is an arithmetic number, because the mean of its divisors is an integer number (3074291731008).

Almost surely, 2^{21520000431251} is an apocalyptic number.

21520000431251 is a deficient number, since it is larger than the sum of its proper divisors (3074333416813).

21520000431251 is an equidigital number, since it uses as much as digits as its factorization.

21520000431251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5955121.

The product of its (nonzero) digits is 2400, while the sum is 26.

Adding to 21520000431251 its reverse (15213400002512), we get a palindrome (36733400433763).

The spelling of 21520000431251 in words is "twenty-one trillion, five hundred twenty billion, four hundred thirty-one thousand, two hundred fifty-one".