21070155 has 16 divisors (see below), whose sum is σ = 33868800. Its totient is φ = 11185248.

The previous prime is 21070121. The next prime is 21070201. The reversal of 21070155 is 55107012.

It is not a de Polignac number, because 21070155 - 2¹⁰ = 21069131 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 196 + ... + 6494.

It is an arithmetic number, because the mean of its divisors is an integer number (2116800).

Almost surely, 2^21070155 is an apocalyptic number.

21070155 is a deficient number, since it is larger than the sum of its proper divisors (12798645).

21070155 is a wasteful number, since it uses less digits than its factorization.

21070155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6530.

The product of its (nonzero) digits is 350, while the sum is 21.

The square root of 21070155 is about 4590.2238507506. The cubic root of 21070155 is about 276.1993020673.

Adding to 21070155 its reverse (55107012), we get a palindrome (76177167).

The spelling of 21070155 in words is "twenty-one million, seventy thousand, one hundred fifty-five".