21931445 has 16 divisors (see below), whose sum is σ = 28289088. Its totient is φ = 16262400.

The previous prime is 21931439. The next prime is 21931447. The reversal of 21931445 is 54413912.

It is not a de Polignac number, because 21931445 - 2¹⁰ = 21930421 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21931447) 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, 3770 + ... + 7620.

It is an arithmetic number, because the mean of its divisors is an integer number (1768068).

Almost surely, 2^21931445 is an apocalyptic number.

It is an amenable number.

21931445 is a deficient number, since it is larger than the sum of its proper divisors (6357643).

21931445 is a wasteful number, since it uses less digits than its factorization.

21931445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3940.

The product of its digits is 4320, while the sum is 29.

The square root of 21931445 is about 4683.1020702094. The cubic root of 21931445 is about 279.9125790010.

The spelling of 21931445 in words is "twenty-one million, nine hundred thirty-one thousand, four hundred forty-five".