21502543401425 has 12 divisors (see below), whose sum is σ = 26663948004876. Its totient is φ = 17201522342400.

The previous prime is 21502543401359. The next prime is 21502543401461. The reversal of 21502543401425 is 52410434520512.

It can be written as a sum of positive squares in 6 ways, for example, as 3372379651216 + 18130163750209 = 1836404^2 + 4257953^2 .

It is not a de Polignac number, because 21502543401425 - 2¹⁸ = 21502543139281 is a prime.

It is a super-3 number, since 3×21502543401425³ (a number of 41 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 11952236 + ... + 13633085.

It is an arithmetic number, because the mean of its divisors is an integer number (2221995667073).

Almost surely, 2^{21502543401425} is an apocalyptic number.

21502543401425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21502543401425 is a deficient number, since it is larger than the sum of its proper divisors (5161404603451).

21502543401425 is a wasteful number, since it uses less digits than its factorization.

21502543401425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25618948 (or 25618943 counting only the distinct ones).

The product of its (nonzero) digits is 192000, while the sum is 38.

Adding to 21502543401425 its reverse (52410434520512), we get a palindrome (73912977921937).

The spelling of 21502543401425 in words is "twenty-one trillion, five hundred two billion, five hundred forty-three million, four hundred one thousand, four hundred twenty-five".