20905623 has 12 divisors (see below), whose sum is σ = 30278248. Its totient is φ = 13899600.

The previous prime is 20905609. The next prime is 20905627. The reversal of 20905623 is 32650902.

It is not a de Polignac number, because 20905623 - 2⁶ = 20905559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20905627) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 648 + ... + 6498.

Almost surely, 2^20905623 is an apocalyptic number.

20905623 is a deficient number, since it is larger than the sum of its proper divisors (9372625).

20905623 is a wasteful number, since it uses less digits than its factorization.

20905623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6254 (or 6251 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 27.

The square root of 20905623 is about 4572.2667245033. The cubic root of 20905623 is about 275.4784969652.

It can be divided in two parts, 20905 and 623, that added together give a triangular number (21528 = T₂₀₇).

The spelling of 20905623 in words is "twenty million, nine hundred five thousand, six hundred twenty-three".