20801520 has 120 divisors (see below), whose sum is σ = 70682976. Its totient is φ = 5481984.

The previous prime is 20801507. The next prime is 20801567. The reversal of 20801520 is 2510802.

It is a tau number, because it is divible by the number of its divisors (120).

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

It is a junction number, because it is equal to n+sod(n) for n = 20801493 and 20801502.

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, 120154 + ... + 120326.

Almost surely, 2^20801520 is an apocalyptic number.

20801520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20801520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35341488).

20801520 is an abundant number, since it is smaller than the sum of its proper divisors (49881456).

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

20801520 is a wasteful number, since it uses less digits than its factorization.

20801520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 359 (or 350 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 20801520 is about 4560.8683383759. The cubic root of 20801520 is about 275.0204723051.

It can be divided in two parts, 20801 and 520, that added together give a triangular number (21321 = T₂₀₆).

The spelling of 20801520 in words is "twenty million, eight hundred one thousand, five hundred twenty".