21920045 has 16 divisors (see below), whose sum is σ = 30557568. Its totient is φ = 14783040.

The previous prime is 21920039. The next prime is 21920047. The reversal of 21920045 is 54002912.

It is not a de Polignac number, because 21920045 - 2⁴ = 21920029 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21920045.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21920047) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2999 + ... + 7268.

It is an arithmetic number, because the mean of its divisors is an integer number (1909848).

Almost surely, 2^21920045 is an apocalyptic number.

It is an amenable number.

21920045 is a deficient number, since it is larger than the sum of its proper divisors (8637523).

21920045 is a wasteful number, since it uses less digits than its factorization.

21920045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10340.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21920045 is about 4681.8847700472. The cubic root of 21920045 is about 279.8640709272.

Adding to 21920045 its reverse (54002912), we get a palindrome (75922957).

The spelling of 21920045 in words is "twenty-one million, nine hundred twenty thousand, forty-five".