20640090 has 16 divisors (see below), whose sum is σ = 49536288. Its totient is φ = 5504016.

The previous prime is 20640089. The next prime is 20640107. The reversal of 20640090 is 9004602.

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, 343972 + ... + 344031.

It is an arithmetic number, because the mean of its divisors is an integer number (3096018).

Almost surely, 2^20640090 is an apocalyptic number.

20640090 is an abundant number, since it is smaller than the sum of its proper divisors (28896198).

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

20640090 is a wasteful number, since it uses less digits than its factorization.

20640090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 688013.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 20640090 is about 4543.1365817021. The cubic root of 20640090 is about 274.3071927160.

Adding to 20640090 its reverse (9004602), we get a palindrome (29644692).

The spelling of 20640090 in words is "twenty million, six hundred forty thousand, ninety".