21010250553 has 4 divisors (see below), whose sum is σ = 28013667408. Its totient is φ = 14006833700.

The previous prime is 21010250531. The next prime is 21010250561. The reversal of 21010250553 is 35505201012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21010250553 - 2⁶ = 21010250489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21010250563) 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, 3501708423 + ... + 3501708428.

It is an arithmetic number, because the mean of its divisors is an integer number (7003416852).

Almost surely, 2^21010250553 is an apocalyptic number.

It is an amenable number.

21010250553 is a deficient number, since it is larger than the sum of its proper divisors (7003416855).

21010250553 is an equidigital number, since it uses as much as digits as its factorization.

21010250553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7003416854.

The product of its (nonzero) digits is 1500, while the sum is 24.

Adding to 21010250553 its reverse (35505201012), we get a palindrome (56515451565).

The spelling of 21010250553 in words is "twenty-one billion, ten million, two hundred fifty thousand, five hundred fifty-three".