21849945 has 32 divisors (see below), whose sum is σ = 38102400. Its totient is φ = 10627584.

The previous prime is 21849941. The next prime is 21849979. The reversal of 21849945 is 54994812.

It is not a de Polignac number, because 21849945 - 2² = 21849941 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21849897 and 21849906.

It is not an unprimeable number, because it can be changed into a prime (21849941) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16726 + ... + 17984.

It is an arithmetic number, because the mean of its divisors is an integer number (1190700).

Almost surely, 2^21849945 is an apocalyptic number.

It is an amenable number.

21849945 is a deficient number, since it is larger than the sum of its proper divisors (16252455).

21849945 is a wasteful number, since it uses less digits than its factorization.

21849945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1369.

The product of its digits is 103680, while the sum is 42.

The square root of 21849945 is about 4674.3924738943. The cubic root of 21849945 is about 279.5654185323.

The spelling of 21849945 in words is "twenty-one million, eight hundred forty-nine thousand, nine hundred forty-five".