21654021 has 16 divisors (see below), whose sum is σ = 29332800. Its totient is φ = 14208000.

The previous prime is 21654019. The next prime is 21654029. The reversal of 21654021 is 12045612.

It is not a de Polignac number, because 21654021 - 2¹ = 21654019 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21654029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 86146 + ... + 86396.

It is an arithmetic number, because the mean of its divisors is an integer number (1833300).

Almost surely, 2^21654021 is an apocalyptic number.

It is an amenable number.

21654021 is a deficient number, since it is larger than the sum of its proper divisors (7678779).

21654021 is a wasteful number, since it uses less digits than its factorization.

21654021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 596.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21654021 is about 4653.3881204989. The cubic root of 21654021 is about 278.7273064301.

Adding to 21654021 its reverse (12045612), we get a palindrome (33699633).

The spelling of 21654021 in words is "twenty-one million, six hundred fifty-four thousand, twenty-one".