21354811 has 4 divisors (see below), whose sum is σ = 21436272. Its totient is φ = 21273352.

The previous prime is 21354799. The next prime is 21354847. The reversal of 21354811 is 11845312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21354811 - 2¹⁵ = 21322043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21354911) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40336 + ... + 40861.

It is an arithmetic number, because the mean of its divisors is an integer number (5359068).

Almost surely, 2^21354811 is an apocalyptic number.

21354811 is a deficient number, since it is larger than the sum of its proper divisors (81461).

21354811 is an equidigital number, since it uses as much as digits as its factorization.

21354811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81460.

The product of its digits is 960, while the sum is 25.

The square root of 21354811 is about 4621.1265942408. The cubic root of 21354811 is about 277.4375521628.

It can be divided in two parts, 213548 and 11, that multiplied together give a triangular number (2349028 = T₂₁₆₇).

The spelling of 21354811 in words is "twenty-one million, three hundred fifty-four thousand, eight hundred eleven".