21232155 has 32 divisors (see below), whose sum is σ = 38997504. Its totient is φ = 9662976.

The previous prime is 21232121. The next prime is 21232157. The reversal of 21232155 is 55123212.

It is not a de Polignac number, because 21232155 - 2⁶ = 21232091 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21232157) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45232 + ... + 45698.

It is an arithmetic number, because the mean of its divisors is an integer number (1218672).

Almost surely, 2^21232155 is an apocalyptic number.

21232155 is a deficient number, since it is larger than the sum of its proper divisors (17765349).

21232155 is a wasteful number, since it uses less digits than its factorization.

21232155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 915.

The product of its digits is 600, while the sum is 21.

The square root of 21232155 is about 4607.8362601117. The cubic root of 21232155 is about 276.9053576329.

Adding to 21232155 its reverse (55123212), we get a palindrome (76355367).

It can be divided in two parts, 2123 and 2155, that added together give a triangular number (4278 = T₉₂).

The spelling of 21232155 in words is "twenty-one million, two hundred thirty-two thousand, one hundred fifty-five".