20120905 has 32 divisors (see below), whose sum is σ = 29491200. Its totient is φ = 12871872.

The previous prime is 20120899. The next prime is 20120923. The reversal of 20120905 is 50902102.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20120905 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 52344 + ... + 52726.

It is an arithmetic number, because the mean of its divisors is an integer number (921600).

Almost surely, 2^20120905 is an apocalyptic number.

It is an amenable number.

20120905 is a deficient number, since it is larger than the sum of its proper divisors (9370295).

20120905 is a wasteful number, since it uses less digits than its factorization.

20120905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 493.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 20120905 is about 4485.6331771557. The cubic root of 20120905 is about 271.9876409105.

It can be divided in two parts, 20120 and 905, that added together give a square (21025 = 145²).

The spelling of 20120905 in words is "twenty million, one hundred twenty thousand, nine hundred five".