21973951 has 4 divisors (see below), whose sum is σ = 21983400. Its totient is φ = 21964504.

The previous prime is 21973933. The next prime is 21973961. The reversal of 21973951 is 15937912.

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 21973951 - 2¹¹ = 21971903 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21973951.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21973961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1485 + ... + 6793.

It is an arithmetic number, because the mean of its divisors is an integer number (5495850).

Almost surely, 2^21973951 is an apocalyptic number.

21973951 is a deficient number, since it is larger than the sum of its proper divisors (9449).

21973951 is an equidigital number, since it uses as much as digits as its factorization.

21973951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9448.

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

The square root of 21973951 is about 4687.6381046322. The cubic root of 21973951 is about 280.0932979906.

The spelling of 21973951 in words is "twenty-one million, nine hundred seventy-three thousand, nine hundred fifty-one".