20491660 has 24 divisors (see below), whose sum is σ = 49180320. Its totient is φ = 7025664.

The previous prime is 20491631. The next prime is 20491699. The reversal of 20491660 is 6619402.

It is a Harshad number since it is a multiple of its sum of digits (28).

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, 73045 + ... + 73324.

It is an arithmetic number, because the mean of its divisors is an integer number (2049180).

Almost surely, 2^20491660 is an apocalyptic number.

20491660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20491660 is an abundant number, since it is smaller than the sum of its proper divisors (28688660).

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

20491660 is a wasteful number, since it uses less digits than its factorization.

20491660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146385 (or 146383 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 20491660 is about 4526.7714764499. The cubic root of 20491660 is about 273.6480643247.

The spelling of 20491660 in words is "twenty million, four hundred ninety-one thousand, six hundred sixty".