21213103550 has 24 divisors (see below), whose sum is σ = 41171869296. Its totient is φ = 8116317440.

The previous prime is 21213103547. The next prime is 21213103567. The reversal of 21213103550 is 5530131212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9221939 + ... + 9224238.

It is an arithmetic number, because the mean of its divisors is an integer number (1715494554).

Almost surely, 2^21213103550 is an apocalyptic number.

21213103550 is a deficient number, since it is larger than the sum of its proper divisors (19958765746).

21213103550 is a wasteful number, since it uses less digits than its factorization.

21213103550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18446212 (or 18446207 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 23.

Adding to 21213103550 its reverse (5530131212), we get a palindrome (26743234762).

The spelling of 21213103550 in words is "twenty-one billion, two hundred thirteen million, one hundred three thousand, five hundred fifty".