21221355251550 has 48 divisors (see below), whose sum is σ = 52632262248192. Its totient is φ = 5658673096800.

The previous prime is 21221355251507. The next prime is 21221355251557. The reversal of 21221355251550 is 5515255312212.

It is a junction number, because it is equal to n+sod(n) for n = 21221355251499 and 21221355251508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221355251557) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2033494 + ... + 6824793.

It is an arithmetic number, because the mean of its divisors is an integer number (1096505463504).

Almost surely, 2^{21221355251550} is an apocalyptic number.

21221355251550 is an abundant number, since it is smaller than the sum of its proper divisors (31410906996642).

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

21221355251550 is a wasteful number, since it uses less digits than its factorization.

21221355251550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8874273 (or 8874268 counting only the distinct ones).

The product of its (nonzero) digits is 150000, while the sum is 39.

The spelling of 21221355251550 in words is "twenty-one trillion, two hundred twenty-one billion, three hundred fifty-five million, two hundred fifty-one thousand, five hundred fifty".