21002253541 has 16 divisors (see below), whose sum is σ = 21481200000. Its totient is φ = 20527788736.

The previous prime is 21002253539. The next prime is 21002253551. The reversal of 21002253541 is 14535220012.

It is a cyclic number.

It is not a de Polignac number, because 21002253541 - 2¹ = 21002253539 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 (21002253521) 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, 8238135 + ... + 8240683.

It is an arithmetic number, because the mean of its divisors is an integer number (1342575000).

Almost surely, 2^21002253541 is an apocalyptic number.

It is an amenable number.

21002253541 is a deficient number, since it is larger than the sum of its proper divisors (478946459).

21002253541 is a wasteful number, since it uses less digits than its factorization.

21002253541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3356.

The product of its (nonzero) digits is 2400, while the sum is 25.

Adding to 21002253541 its reverse (14535220012), we get a palindrome (35537473553).

The spelling of 21002253541 in words is "twenty-one billion, two million, two hundred fifty-three thousand, five hundred forty-one".