20491390 has 48 divisors (see below), whose sum is σ = 40194144. Its totient is φ = 7504640.

The previous prime is 20491379. The next prime is 20491399. The reversal of 20491390 is 9319402.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20491399) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 386604 + ... + 386656.

It is an arithmetic number, because the mean of its divisors is an integer number (837378).

Almost surely, 2^20491390 is an apocalyptic number.

20491390 is a deficient number, since it is larger than the sum of its proper divisors (19702754).

20491390 is a wasteful number, since it uses less digits than its factorization.

20491390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165 (or 124 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 20491390 is about 4526.7416537726. The cubic root of 20491390 is about 273.6468624487.

The spelling of 20491390 in words is "twenty million, four hundred ninety-one thousand, three hundred ninety".