20645408 has 96 divisors (see below), whose sum is σ = 49641984. Its totient is φ = 8266752.

The previous prime is 20645407. The next prime is 20645413. The reversal of 20645408 is 80454602.

It is not an unprimeable number, because it can be changed into a prime (20645407) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 389510 + ... + 389562.

It is an arithmetic number, because the mean of its divisors is an integer number (517104).

Almost surely, 2^20645408 is an apocalyptic number.

20645408 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 20645408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24820992).

20645408 is an abundant number, since it is smaller than the sum of its proper divisors (28996576).

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

20645408 is a wasteful number, since it uses less digits than its factorization.

20645408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154 (or 146 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 29.

The square root of 20645408 is about 4543.7218224711. The cubic root of 20645408 is about 274.3307494670.

The spelling of 20645408 in words is "twenty million, six hundred forty-five thousand, four hundred eight".