20491888 has 10 divisors (see below), whose sum is σ = 39703064. Its totient is φ = 10245936.

The previous prime is 20491853. The next prime is 20491897. The reversal of 20491888 is 88819402.

It is a self number, because there is not a number n which added to its sum of digits gives 20491888.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 640356 + ... + 640387.

Almost surely, 2^20491888 is an apocalyptic number.

It is an amenable number.

20491888 is a deficient number, since it is larger than the sum of its proper divisors (19211176).

20491888 is a wasteful number, since it uses less digits than its factorization.

20491888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1280751 (or 1280745 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 40.

The square root of 20491888 is about 4526.7966598910. The cubic root of 20491888 is about 273.6490792340.

The spelling of 20491888 in words is "twenty million, four hundred ninety-one thousand, eight hundred eighty-eight".