21954791 has 4 divisors (see below), whose sum is σ = 21965712. Its totient is φ = 21943872.

The previous prime is 21954767. The next prime is 21954799. The reversal of 21954791 is 19745912.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21954791 - 2¹⁸ = 21692647 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21954799) 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, 1475 + ... + 6788.

It is an arithmetic number, because the mean of its divisors is an integer number (5491428).

Almost surely, 2^21954791 is an apocalyptic number.

21954791 is a deficient number, since it is larger than the sum of its proper divisors (10921).

21954791 is an equidigital number, since it uses as much as digits as its factorization.

21954791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10920.

The product of its digits is 22680, while the sum is 38.

The square root of 21954791 is about 4685.5939858251. The cubic root of 21954791 is about 280.0118659937.

The spelling of 21954791 in words is "twenty-one million, nine hundred fifty-four thousand, seven hundred ninety-one".