21311398 has 16 divisors (see below), whose sum is σ = 32845824. Its totient is φ = 10365640.

The previous prime is 21311393. The next prime is 21311399. The reversal of 21311398 is 89311312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311393) 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 7 ways as a sum of consecutive naturals, for example, 17361 + ... + 18547.

It is an arithmetic number, because the mean of its divisors is an integer number (2052864).

Almost surely, 2^21311398 is an apocalyptic number.

21311398 is a deficient number, since it is larger than the sum of its proper divisors (11534426).

21311398 is a wasteful number, since it uses less digits than its factorization.

21311398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1427.

The product of its digits is 1296, while the sum is 28.

The square root of 21311398 is about 4616.4269733204. The cubic root of 21311398 is about 277.2494202001.

It can be divided in two parts, 213 and 11398, that added together give a palindrome (11611).

The spelling of 21311398 in words is "twenty-one million, three hundred eleven thousand, three hundred ninety-eight".