21645954 has 48 divisors (see below), whose sum is σ = 53071200. Its totient is φ = 6557760.

The previous prime is 21645937. The next prime is 21646003. The reversal of 21645954 is 45954612.

21645954 is a `hidden beast` number, since 2 + 1 + 64 + 595 + 4 = 666.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3322 + ... + 7370.

It is an arithmetic number, because the mean of its divisors is an integer number (1105650).

Almost surely, 2^21645954 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21645954, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26535600).

21645954 is an abundant number, since it is smaller than the sum of its proper divisors (31425246).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21645954 is a wasteful number, since it uses less digits than its factorization.

21645954 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4077 (or 4065 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 21645954 is about 4652.5212519665. The cubic root of 21645954 is about 278.6926897268.

It can be divided in two parts, 2164 and 5954, that added together give a palindrome (8118).

The spelling of 21645954 in words is "twenty-one million, six hundred forty-five thousand, nine hundred fifty-four".