20605640 has 32 divisors (see below), whose sum is σ = 50578560. Its totient is φ = 7492800.

The previous prime is 20605621. The next prime is 20605661. The reversal of 20605640 is 4650602.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22976 + ... + 23855.

It is an arithmetic number, because the mean of its divisors is an integer number (1580580).

Almost surely, 2^20605640 is an apocalyptic number.

20605640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20605640 is an abundant number, since it is smaller than the sum of its proper divisors (29972920).

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

20605640 is a wasteful number, since it uses less digits than its factorization.

20605640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46853 (or 46849 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 20605640 is about 4539.3435648781. The cubic root of 20605640 is about 274.1544940082.

The spelling of 20605640 in words is "twenty million, six hundred five thousand, six hundred forty".