21111387 has 8 divisors (see below), whose sum is σ = 30707520. Its totient is φ = 12794760.

The previous prime is 21111383. The next prime is 21111397. The reversal of 21111387 is 78311112.

It is a happy number.

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

It is not a de Polignac number, because 21111387 - 2² = 21111383 is a prime.

It is a super-2 number, since 2×21111387² = 891381322127538, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21111383) 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, 319837 + ... + 319902.

It is an arithmetic number, because the mean of its divisors is an integer number (3838440).

Almost surely, 2^21111387 is an apocalyptic number.

21111387 is a deficient number, since it is larger than the sum of its proper divisors (9596133).

21111387 is a wasteful number, since it uses less digits than its factorization.

21111387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 639753.

The product of its digits is 336, while the sum is 24.

The square root of 21111387 is about 4594.7129398908. The cubic root of 21111387 is about 276.3793486651.

Adding to 21111387 its reverse (78311112), we get a palindrome (99422499).

The spelling of 21111387 in words is "twenty-one million, one hundred eleven thousand, three hundred eighty-seven".