21105451 has 8 divisors (see below), whose sum is σ = 22145408. Its totient is φ = 20088000.

The previous prime is 21105443. The next prime is 21105457. The reversal of 21105451 is 15450112.

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

It is not a de Polignac number, because 21105451 - 2³ = 21105443 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21105457) 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, 3690 + ... + 7471.

It is an arithmetic number, because the mean of its divisors is an integer number (2768176).

Almost surely, 2^21105451 is an apocalyptic number.

21105451 is a deficient number, since it is larger than the sum of its proper divisors (1039957).

21105451 is a wasteful number, since it uses less digits than its factorization.

21105451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11253.

The product of its (nonzero) digits is 200, while the sum is 19.

The square root of 21105451 is about 4594.0669346452. The cubic root of 21105451 is about 276.3534425573.

Adding to 21105451 its reverse (15450112), we get a palindrome (36555563).

The spelling of 21105451 in words is "twenty-one million, one hundred five thousand, four hundred fifty-one".