21155405520450 has 96 divisors (see below), whose sum is σ = 55557951456384. Its totient is φ = 5308985482240.

The previous prime is 21155405520421. The next prime is 21155405520461. The reversal of 21155405520450 is 5402550455112.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21155405520399 and 21155405520408.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 22064947 + ... + 23003753.

It is an arithmetic number, because the mean of its divisors is an integer number (578728661004).

Almost surely, 2^{21155405520450} is an apocalyptic number.

21155405520450 is an abundant number, since it is smaller than the sum of its proper divisors (34402545935934).

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

21155405520450 is a wasteful number, since it uses less digits than its factorization.

21155405520450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 947676 (or 947671 counting only the distinct ones).

The product of its (nonzero) digits is 200000, while the sum is 39.

Adding to 21155405520450 its reverse (5402550455112), we get a palindrome (26557955975562).

The spelling of 21155405520450 in words is "twenty-one trillion, one hundred fifty-five billion, four hundred five million, five hundred twenty thousand, four hundred fifty".