21219145 has 16 divisors (see below), whose sum is σ = 27122688. Its totient is φ = 15880960.

The previous prime is 21219127. The next prime is 21219161. The reversal of 21219145 is 54191212.

It is a happy number.

It is not a de Polignac number, because 21219145 - 2²³ = 12830537 is a prime.

It is a super-2 number, since 2×21219145² = 900504229062050, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15582 + ... + 16888.

It is an arithmetic number, because the mean of its divisors is an integer number (1695168).

Almost surely, 2^21219145 is an apocalyptic number.

It is an amenable number.

21219145 is a deficient number, since it is larger than the sum of its proper divisors (5903543).

21219145 is a wasteful number, since it uses less digits than its factorization.

21219145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1520.

The product of its digits is 720, while the sum is 25.

The square root of 21219145 is about 4606.4243182755. The cubic root of 21219145 is about 276.8487881706.

The spelling of 21219145 in words is "twenty-one million, two hundred nineteen thousand, one hundred forty-five".