21912945 has 8 divisors (see below), whose sum is σ = 35060736. Its totient is φ = 11686896.

The previous prime is 21912931. The next prime is 21912967. The reversal of 21912945 is 54921912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21912945 - 2¹² = 21908849 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 730417 + ... + 730446.

It is an arithmetic number, because the mean of its divisors is an integer number (4382592).

Almost surely, 2^21912945 is an apocalyptic number.

It is an amenable number.

21912945 is a deficient number, since it is larger than the sum of its proper divisors (13147791).

21912945 is a wasteful number, since it uses less digits than its factorization.

21912945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1460871.

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

The square root of 21912945 is about 4681.1264669949. The cubic root of 21912945 is about 279.8338512587.

The spelling of 21912945 in words is "twenty-one million, nine hundred twelve thousand, nine hundred forty-five".