21253100262461 has 4 divisors (see below), whose sum is σ = 21281175692892. Its totient is φ = 21225024832032.

The previous prime is 21253100262451. The next prime is 21253100262463. The reversal of 21253100262461 is 16426200135212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 16244075795236 + 5009024467225 = 4030394^2 + 2238085^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21253100262461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253100262463) 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, 14037714080 + ... + 14037715593.

It is an arithmetic number, because the mean of its divisors is an integer number (5320293923223).

Almost surely, 2^{21253100262461} is an apocalyptic number.

It is an amenable number.

21253100262461 is a deficient number, since it is larger than the sum of its proper divisors (28075430431).

21253100262461 is an equidigital number, since it uses as much as digits as its factorization.

21253100262461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28075430430.

The product of its (nonzero) digits is 34560, while the sum is 35.

Adding to 21253100262461 its reverse (16426200135212), we get a palindrome (37679300397673).

The spelling of 21253100262461 in words is "twenty-one trillion, two hundred fifty-three billion, one hundred million, two hundred sixty-two thousand, four hundred sixty-one".