20505408 has 224 divisors, whose sum is σ = 72176640. Its totient is φ = 4976640.

The previous prime is 20505379. The next prime is 20505409. The reversal of 20505408 is 80450502.

It is a tau number, because it is divible by the number of its divisors (224).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20505409) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 280860 + ... + 280932.

Almost surely, 2^20505408 is an apocalyptic number.

20505408 is a gapful number since it is divisible by the number (28) 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 20505408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36088320).

20505408 is an abundant number, since it is smaller than the sum of its proper divisors (51671232).

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

20505408 is a wasteful number, since it uses less digits than its factorization.

20505408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125 (or 115 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 24.

The square root of 20505408 is about 4528.2897433799. The cubic root of 20505408 is about 273.7092481195.

The spelling of 20505408 in words is "twenty million, five hundred five thousand, four hundred eight".