21000404253 has 16 divisors (see below), whose sum is σ = 28052087616. Its totient is φ = 13974522240.

The previous prime is 21000404251. The next prime is 21000404263. The reversal of 21000404253 is 35240400012.

It is not a de Polignac number, because 21000404253 - 2¹ = 21000404251 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000404251) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5318626 + ... + 5322572.

It is an arithmetic number, because the mean of its divisors is an integer number (1753255476).

Almost surely, 2^21000404253 is an apocalyptic number.

It is an amenable number.

21000404253 is a deficient number, since it is larger than the sum of its proper divisors (7051683363).

21000404253 is a wasteful number, since it uses less digits than its factorization.

21000404253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6764.

The product of its (nonzero) digits is 960, while the sum is 21.

Adding to 21000404253 its reverse (35240400012), we get a palindrome (56240804265).

The spelling of 21000404253 in words is "twenty-one billion, four hundred four thousand, two hundred fifty-three".