20021550 has 48 divisors (see below), whose sum is σ = 50092032. Its totient is φ = 5292000.

The previous prime is 20021549. The next prime is 20021623. The reversal of 20021550 is 5512002.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18525 + ... + 19575.

It is an arithmetic number, because the mean of its divisors is an integer number (1043584).

Almost surely, 2^20021550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20021550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25046016).

20021550 is an abundant number, since it is smaller than the sum of its proper divisors (30070482).

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

20021550 is a wasteful number, since it uses less digits than its factorization.

20021550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1193 (or 1188 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 20021550 is about 4474.5446695725. The cubic root of 20021550 is about 271.5392194970.

Adding to 20021550 its reverse (5512002), we get a palindrome (25533552).

The spelling of 20021550 in words is "twenty million, twenty-one thousand, five hundred fifty".