21388577 has 8 divisors (see below), whose sum is σ = 24623616. Its totient is φ = 18198432.

The previous prime is 21388559. The next prime is 21388583. The reversal of 21388577 is 77588312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21388577 - 2²² = 17194273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21388517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10193 + ... + 12110.

It is an arithmetic number, because the mean of its divisors is an integer number (3077952).

Almost surely, 2^21388577 is an apocalyptic number.

It is an amenable number.

21388577 is a deficient number, since it is larger than the sum of its proper divisors (3235039).

21388577 is a wasteful number, since it uses less digits than its factorization.

21388577 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22447.

The product of its digits is 94080, while the sum is 41.

The square root of 21388577 is about 4624.7785892948. The cubic root of 21388577 is about 277.5837022617.

The spelling of 21388577 in words is "twenty-one million, three hundred eighty-eight thousand, five hundred seventy-seven".