21201343551 has 48 divisors (see below), whose sum is σ = 31365734400. Its totient is φ = 13797532224.

The previous prime is 21201343547. The next prime is 21201343573. The reversal of 21201343551 is 15534310212.

21201343551 is a `hidden beast` number, since 21 + 201 + 3 + 435 + 5 + 1 = 666.

It is not a de Polignac number, because 21201343551 - 2² = 21201343547 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201343151) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 20805520 + ... + 20806538.

It is an arithmetic number, because the mean of its divisors is an integer number (653452800).

Almost surely, 2^21201343551 is an apocalyptic number.

21201343551 is a deficient number, since it is larger than the sum of its proper divisors (10164390849).

21201343551 is a wasteful number, since it uses less digits than its factorization.

21201343551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1428 (or 1425 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

Adding to 21201343551 its reverse (15534310212), we get a palindrome (36735653763).

The spelling of 21201343551 in words is "twenty-one billion, two hundred one million, three hundred forty-three thousand, five hundred fifty-one".