20520390 has 48 divisors (see below), whose sum is σ = 54142704. Its totient is φ = 4973760.

The previous prime is 20520389. The next prime is 20520403. The reversal of 20520390 is 9302502.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 804 + ... + 6456.

It is an arithmetic number, because the mean of its divisors is an integer number (1127973).

Almost surely, 2^20520390 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20520390, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27071352).

20520390 is an abundant number, since it is smaller than the sum of its proper divisors (33622314).

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

20520390 is a wasteful number, since it uses less digits than its factorization.

20520390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5685 (or 5674 counting only the distinct ones).

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 20520390 is about 4529.9437082595. The cubic root of 20520390 is about 273.7758925489.

Adding to 20520390 its reverse (9302502), we get a palindrome (29822892).

It can be divided in two parts, 20520 and 390, that added together give a triangular number (20910 = T₂₀₄).

The spelling of 20520390 in words is "twenty million, five hundred twenty thousand, three hundred ninety".