20015550 has 72 divisors (see below), whose sum is σ = 56629560. Its totient is φ = 5054400.

The previous prime is 20015537. The next prime is 20015551. The reversal of 20015550 is 5551002.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20015551) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 7380 + ... + 9720.

Almost surely, 2^20015550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20015550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28314780).

20015550 is an abundant number, since it is smaller than the sum of its proper divisors (36614010).

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

20015550 is a wasteful number, since it uses less digits than its factorization.

20015550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2378 (or 2370 counting only the distinct ones).

The product of its (nonzero) digits is 250, while the sum is 18.

The square root of 20015550 is about 4473.8741600541. The cubic root of 20015550 is about 271.5120920919.

Adding to 20015550 its reverse (5551002), we get a palindrome (25566552).

The spelling of 20015550 in words is "twenty million, fifteen thousand, five hundred fifty".