20551720 has 64 divisors (see below), whose sum is σ = 54691200. Its totient is φ = 6800640.

The previous prime is 20551703. The next prime is 20551733. The reversal of 20551720 is 2715502.

20551720 = T₁₁₇₆ + T₁₁₇₇ + ... + T₁₂₀₄.

It is a junction number, because it is equal to n+sod(n) for n = 20551691 and 20551700.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6855 + ... + 9385.

It is an arithmetic number, because the mean of its divisors is an integer number (854550).

Almost surely, 2^20551720 is an apocalyptic number.

20551720 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 20551720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27345600).

20551720 is an abundant number, since it is smaller than the sum of its proper divisors (34139480).

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

20551720 is a wasteful number, since it uses less digits than its factorization.

20551720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2578 (or 2574 counting only the distinct ones).

The product of its (nonzero) digits is 700, while the sum is 22.

The square root of 20551720 is about 4533.4004896987. The cubic root of 20551720 is about 273.9151530139.

The spelling of 20551720 in words is "twenty million, five hundred fifty-one thousand, seven hundred twenty".