21820154 has 4 divisors (see below), whose sum is σ = 32730234. Its totient is φ = 10910076.

The previous prime is 21820133. The next prime is 21820157. The reversal of 21820154 is 45102812.

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

It can be written as a sum of positive squares in only one way, i.e., 17098225 + 4721929 = 4135^2 + 2173^2 .

It is a super-2 number, since 2×21820154² = 952238241167432, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21820157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5455037 + ... + 5455040.

Almost surely, 2^21820154 is an apocalyptic number.

21820154 is a deficient number, since it is larger than the sum of its proper divisors (10910080).

21820154 is a wasteful number, since it uses less digits than its factorization.

21820154 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10910079.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21820154 is about 4671.2047696499. The cubic root of 21820154 is about 279.4383042322.

Adding to 21820154 its reverse (45102812), we get a palindrome (66922966).

The spelling of 21820154 in words is "twenty-one million, eight hundred twenty thousand, one hundred fifty-four".