21376399 has 16 divisors (see below), whose sum is σ = 24053760. Its totient is φ = 18830560.

The previous prime is 21376357. The next prime is 21376403. The reversal of 21376399 is 99367312.

21376399 = 172² + 173² + ... + 410².

It is a cyclic number.

It is not a de Polignac number, because 21376399 - 2¹¹ = 21374351 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21376319) 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 15 ways as a sum of consecutive naturals, for example, 89322 + ... + 89560.

It is an arithmetic number, because the mean of its divisors is an integer number (1503360).

Almost surely, 2^21376399 is an apocalyptic number.

21376399 is a deficient number, since it is larger than the sum of its proper divisors (2677361).

21376399 is a wasteful number, since it uses less digits than its factorization.

21376399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 470.

The product of its digits is 61236, while the sum is 40.

The square root of 21376399 is about 4623.4617982633. The cubic root of 21376399 is about 277.5310097100.

The spelling of 21376399 in words is "twenty-one million, three hundred seventy-six thousand, three hundred ninety-nine".