21907345 has 4 divisors (see below), whose sum is σ = 26288820. Its totient is φ = 17525872.

The previous prime is 21907307. The next prime is 21907351. The reversal of 21907345 is 54370912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6170256 + 15737089 = 2484^2 + 3967^2 .

It is a cyclic number.

It is not a de Polignac number, because 21907345 - 2¹¹ = 21905297 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2190730 + ... + 2190739.

It is an arithmetic number, because the mean of its divisors is an integer number (6572205).

Almost surely, 2^21907345 is an apocalyptic number.

It is an amenable number.

21907345 is a deficient number, since it is larger than the sum of its proper divisors (4381475).

21907345 is an equidigital number, since it uses as much as digits as its factorization.

21907345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4381474.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 21907345 is about 4680.5282821494. The cubic root of 21907345 is about 279.8100114222.

The spelling of 21907345 in words is "twenty-one million, nine hundred seven thousand, three hundred forty-five".