21402907 has 4 divisors (see below), whose sum is σ = 21858336. Its totient is φ = 20947480.

The previous prime is 21402893. The next prime is 21402919. The reversal of 21402907 is 70920412.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21402907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21402947) 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, 227644 + ... + 227737.

It is an arithmetic number, because the mean of its divisors is an integer number (5464584).

Almost surely, 2^21402907 is an apocalyptic number.

21402907 is a deficient number, since it is larger than the sum of its proper divisors (455429).

21402907 is an equidigital number, since it uses as much as digits as its factorization.

21402907 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 455428.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21402907 is about 4626.3275932428. The cubic root of 21402907 is about 277.6456806164.

The spelling of 21402907 in words is "twenty-one million, four hundred two thousand, nine hundred seven".