21388611 has 8 divisors (see below), whose sum is σ = 28944064. Its totient is φ = 14046120.

The previous prime is 21388607. The next prime is 21388639. The reversal of 21388611 is 11688312.

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

It is not a de Polignac number, because 21388611 - 2² = 21388607 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21388651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 53005 + ... + 53406.

It is an arithmetic number, because the mean of its divisors is an integer number (3618008).

Almost surely, 2^21388611 is an apocalyptic number.

21388611 is a deficient number, since it is larger than the sum of its proper divisors (7555453).

21388611 is a wasteful number, since it uses less digits than its factorization.

21388611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106481.

The product of its digits is 2304, while the sum is 30.

The square root of 21388611 is about 4624.7822651450. The cubic root of 21388611 is about 277.5838493470.

The spelling of 21388611 in words is "twenty-one million, three hundred eighty-eight thousand, six hundred eleven".