21155440250 has 256 divisors, whose sum is σ = 49376231424. Its totient is φ = 6630624000.

The previous prime is 21155440247. The next prime is 21155440279. The reversal of 21155440250 is 5204455112.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 100262645 + ... + 100262855.

It is an arithmetic number, because the mean of its divisors is an integer number (192875904).

Almost surely, 2^21155440250 is an apocalyptic number.

21155440250 is an abundant number, since it is smaller than the sum of its proper divisors (28220791174).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21155440250 is a wasteful number, since it uses less digits than its factorization.

21155440250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 358 (or 348 counting only the distinct ones).

The product of its (nonzero) digits is 8000, while the sum is 29.

Adding to 21155440250 its reverse (5204455112), we get a palindrome (26359895362).

The spelling of 21155440250 in words is "twenty-one billion, one hundred fifty-five million, four hundred forty thousand, two hundred fifty".