21201154550 has 24 divisors (see below), whose sum is σ = 39444870456. Its totient is φ = 8478155840.

The previous prime is 21201154537. The next prime is 21201154553. The reversal of 21201154550 is 5545110212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201154553) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 134402 + ... + 245898.

It is an arithmetic number, because the mean of its divisors is an integer number (1643536269).

Almost surely, 2^21201154550 is an apocalyptic number.

21201154550 is a deficient number, since it is larger than the sum of its proper divisors (18243715906).

21201154550 is a wasteful number, since it uses less digits than its factorization.

21201154550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115312 (or 115307 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 26.

Adding to 21201154550 its reverse (5545110212), we get a palindrome (26746264762).

The spelling of 21201154550 in words is "twenty-one billion, two hundred one million, one hundred fifty-four thousand, five hundred fifty".