21040455 has 8 divisors (see below), whose sum is σ = 33664752. Its totient is φ = 11221568.

The previous prime is 21040447. The next prime is 21040463. The reversal of 21040455 is 55404012.

It is an interprime number because it is at equal distance from previous prime (21040447) and next prime (21040463).

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

It is a cyclic number.

It is not a de Polignac number, because 21040455 - 2³ = 21040447 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 701334 + ... + 701363.

It is an arithmetic number, because the mean of its divisors is an integer number (4208094).

Almost surely, 2^21040455 is an apocalyptic number.

21040455 is a deficient number, since it is larger than the sum of its proper divisors (12624297).

21040455 is a wasteful number, since it uses less digits than its factorization.

21040455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1402705.

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 21040455 is about 4586.9875735607. The cubic root of 21040455 is about 276.0694663415.

Adding to 21040455 its reverse (55404012), we get a palindrome (76444467).

The spelling of 21040455 in words is "twenty-one million, forty thousand, four hundred fifty-five".