21206154 has 8 divisors (see below), whose sum is σ = 42412320. Its totient is φ = 7068716.

The previous prime is 21206131. The next prime is 21206173. The reversal of 21206154 is 45160212.

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

21206154 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 21206154.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1767174 + ... + 1767185.

It is an arithmetic number, because the mean of its divisors is an integer number (5301540).

Almost surely, 2^21206154 is an apocalyptic number.

21206154 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21206154 is a wasteful number, since it uses less digits than its factorization.

21206154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3534364.

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

The square root of 21206154 is about 4605.0140064934. The cubic root of 21206154 is about 276.7922782464.

Adding to 21206154 its reverse (45160212), we get a palindrome (66366366).

It can be divided in two parts, 21 and 206154, that multiplied together give a palindrome (4329234).

The spelling of 21206154 in words is "twenty-one million, two hundred six thousand, one hundred fifty-four".