20919639 has 32 divisors (see below), whose sum is σ = 32175360. Its totient is φ = 11976192.

The previous prime is 20919631. The next prime is 20919641. The reversal of 20919639 is 93691902.

It is a happy number.

It is not a de Polignac number, because 20919639 - 2³ = 20919631 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a junction number, because it is equal to n+sod(n) for n = 20919597 and 20919606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20919631) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 92044 + ... + 92270.

It is an arithmetic number, because the mean of its divisors is an integer number (1005480).

Almost surely, 2^20919639 is an apocalyptic number.

20919639 is a deficient number, since it is larger than the sum of its proper divisors (11255721).

20919639 is a wasteful number, since it uses less digits than its factorization.

20919639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 399.

The product of its (nonzero) digits is 26244, while the sum is 39.

The square root of 20919639 is about 4573.7991866718. The cubic root of 20919639 is about 275.5400472963.

The spelling of 20919639 in words is "twenty million, nine hundred nineteen thousand, six hundred thirty-nine".