21000455 has 16 divisors (see below), whose sum is σ = 29346624. Its totient is φ = 14127360.

The previous prime is 21000433. The next prime is 21000461. The reversal of 21000455 is 55400012.

It is not a de Polignac number, because 21000455 - 2⁶ = 21000391 is a prime.

It is a super-2 number, since 2×21000455² = 882038220414050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3806 + ... + 7515.

It is an arithmetic number, because the mean of its divisors is an integer number (1834164).

Almost surely, 2^21000455 is an apocalyptic number.

21000455 is a deficient number, since it is larger than the sum of its proper divisors (8346169).

21000455 is a wasteful number, since it uses less digits than its factorization.

21000455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11386.

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 21000455 is about 4582.6253392570. The cubic root of 21000455 is about 275.8944101801.

Adding to 21000455 its reverse (55400012), we get a palindrome (76400467).

The spelling of 21000455 in words is "twenty-one million, four hundred fifty-five", and thus it is an aban number.