21643154 has 12 divisors (see below), whose sum is σ = 35154666. Its totient is φ = 9988992.

The previous prime is 21643129. The next prime is 21643183. The reversal of 21643154 is 45134612.

It can be written as a sum of positive squares in 3 ways, for example, as 16999129 + 4644025 = 4123^2 + 2155^2 .

It is a super-2 number, since 2×21643154² = 936852230135432, which contains 22 as substring.

It is a Smith number, since the sum of its digits (26) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 31679 + ... + 32354.

Almost surely, 2^21643154 is an apocalyptic number.

21643154 is a deficient number, since it is larger than the sum of its proper divisors (13511512).

21643154 is a wasteful number, since it uses less digits than its factorization.

21643154 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64061 (or 64048 counting only the distinct ones).

The product of its digits is 2880, while the sum is 26.

The square root of 21643154 is about 4652.2203301220. The cubic root of 21643154 is about 278.6806724975.

Adding to 21643154 its reverse (45134612), we get a palindrome (66777766).

The spelling of 21643154 in words is "twenty-one million, six hundred forty-three thousand, one hundred fifty-four".