21945219 has 16 divisors (see below), whose sum is σ = 29736960. Its totient is φ = 14394240.

The previous prime is 21945211. The next prime is 21945229. The reversal of 21945219 is 91254912.

It is not a de Polignac number, because 21945219 - 2³ = 21945211 is a prime.

It is a super-2 number, since 2×21945219² = 963185273915922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21945219.

It is not an unprimeable number, because it can be changed into a prime (21945211) 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, 90939 + ... + 91179.

It is an arithmetic number, because the mean of its divisors is an integer number (1858560).

Almost surely, 2^21945219 is an apocalyptic number.

21945219 is a deficient number, since it is larger than the sum of its proper divisors (7791741).

21945219 is a wasteful number, since it uses less digits than its factorization.

21945219 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610.

The product of its digits is 6480, while the sum is 33.

The square root of 21945219 is about 4684.5724458055. The cubic root of 21945219 is about 279.9711662486.

The spelling of 21945219 in words is "twenty-one million, nine hundred forty-five thousand, two hundred nineteen".