21951379 has 4 divisors (see below), whose sum is σ = 22659520. Its totient is φ = 21243240.

The previous prime is 21951367. The next prime is 21951383. The reversal of 21951379 is 97315912.

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

It is a cyclic number.

It is not a de Polignac number, because 21951379 - 2¹¹ = 21949331 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21951329) 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, 354024 + ... + 354085.

It is an arithmetic number, because the mean of its divisors is an integer number (5664880).

Almost surely, 2^21951379 is an apocalyptic number.

21951379 is a deficient number, since it is larger than the sum of its proper divisors (708141).

21951379 is an equidigital number, since it uses as much as digits as its factorization.

21951379 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 708140.

The product of its digits is 17010, while the sum is 37.

The square root of 21951379 is about 4685.2298769644. The cubic root of 21951379 is about 279.9973596690.

The spelling of 21951379 in words is "twenty-one million, nine hundred fifty-one thousand, three hundred seventy-nine".