21445897 has 4 divisors (see below), whose sum is σ = 23395536. Its totient is φ = 19496260.

The previous prime is 21445873. The next prime is 21445909. The reversal of 21445897 is 79854412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21445897 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21445807) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 974803 + ... + 974824.

It is an arithmetic number, because the mean of its divisors is an integer number (5848884).

Almost surely, 2^21445897 is an apocalyptic number.

It is an amenable number.

21445897 is a deficient number, since it is larger than the sum of its proper divisors (1949639).

21445897 is a wasteful number, since it uses less digits than its factorization.

21445897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1949638.

The product of its digits is 80640, while the sum is 40.

The square root of 21445897 is about 4630.9714963493. The cubic root of 21445897 is about 277.8314498540.

The spelling of 21445897 in words is "twenty-one million, four hundred forty-five thousand, eight hundred ninety-seven".