21860155 has 8 divisors (see below), whose sum is σ = 26941392. Its totient is φ = 17015328.

The previous prime is 21860117. The next prime is 21860183. The reversal of 21860155 is 55106812.

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

It is a cyclic number.

It is not a de Polignac number, because 21860155 - 2¹⁵ = 21827387 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 58897 + ... + 59266.

It is an arithmetic number, because the mean of its divisors is an integer number (3367674).

Almost surely, 2^21860155 is an apocalyptic number.

21860155 is a deficient number, since it is larger than the sum of its proper divisors (5081237).

21860155 is a wasteful number, since it uses less digits than its factorization.

21860155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118205.

The product of its (nonzero) digits is 2400, while the sum is 28.

The square root of 21860155 is about 4675.4844668761. The cubic root of 21860155 is about 279.6089566807.

Adding to 21860155 its reverse (55106812), we get a palindrome (76966967).

The spelling of 21860155 in words is "twenty-one million, eight hundred sixty thousand, one hundred fifty-five".