21927649 has 4 divisors (see below), whose sum is σ = 21942036. Its totient is φ = 21913264.

The previous prime is 21927641. The next prime is 21927673. The reversal of 21927649 is 94672912.

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 3265249 + 18662400 = 1807^2 + 4320^2 .

It is a cyclic number.

It is not a de Polignac number, because 21927649 - 2³ = 21927641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21927641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4594 + ... + 8059.

It is an arithmetic number, because the mean of its divisors is an integer number (5485509).

Almost surely, 2^21927649 is an apocalyptic number.

It is an amenable number.

21927649 is a deficient number, since it is larger than the sum of its proper divisors (14387).

21927649 is a wasteful number, since it uses less digits than its factorization.

21927649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14386.

The product of its digits is 54432, while the sum is 40.

The square root of 21927649 is about 4682.6967657537. The cubic root of 21927649 is about 279.8964285306.

The spelling of 21927649 in words is "twenty-one million, nine hundred twenty-seven thousand, six hundred forty-nine".