21190155 has 32 divisors (see below), whose sum is σ = 40089600. Its totient is φ = 9351552.

The previous prime is 21190151. The next prime is 21190171. The reversal of 21190155 is 55109112.

It is not a de Polignac number, because 21190155 - 2² = 21190151 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21190151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 435 + ... + 6524.

It is an arithmetic number, because the mean of its divisors is an integer number (1252800).

Almost surely, 2^21190155 is an apocalyptic number.

21190155 is a deficient number, since it is larger than the sum of its proper divisors (18899445).

21190155 is a wasteful number, since it uses less digits than its factorization.

21190155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7003.

The product of its (nonzero) digits is 450, while the sum is 24.

The square root of 21190155 is about 4603.2765504584. The cubic root of 21190155 is about 276.7226520144.

Adding to 21190155 its reverse (55109112), we get a palindrome (76299267).

The spelling of 21190155 in words is "twenty-one million, one hundred ninety thousand, one hundred fifty-five".