21354681 has 8 divisors (see below), whose sum is σ = 28749760. Its totient is φ = 14098032.

The previous prime is 21354667. The next prime is 21354721. The reversal of 21354681 is 18645312.

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

It is not a de Polignac number, because 21354681 - 2¹³ = 21346489 is a prime.

It is a super-2 number, since 2×21354681² = 912044801223522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21354181) 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 7 ways as a sum of consecutive naturals, for example, 34246 + ... + 34863.

It is an arithmetic number, because the mean of its divisors is an integer number (3593720).

Almost surely, 2^21354681 is an apocalyptic number.

It is an amenable number.

21354681 is a deficient number, since it is larger than the sum of its proper divisors (7395079).

21354681 is a wasteful number, since it uses less digits than its factorization.

21354681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69215.

The product of its digits is 5760, while the sum is 30.

The square root of 21354681 is about 4621.1125283853. The cubic root of 21354681 is about 277.4369891834.

Adding to 21354681 its reverse (18645312), we get a palindrome (39999993).

The spelling of 21354681 in words is "twenty-one million, three hundred fifty-four thousand, six hundred eighty-one".