21212955 has 16 divisors (see below), whose sum is σ = 37712160. Its totient is φ = 11313504.

The previous prime is 21212941. The next prime is 21212977. The reversal of 21212955 is 55921212.

It is not a de Polignac number, because 21212955 - 2¹¹ = 21210907 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 78432 + ... + 78701.

It is an arithmetic number, because the mean of its divisors is an integer number (2357010).

Almost surely, 2^21212955 is an apocalyptic number.

21212955 is a deficient number, since it is larger than the sum of its proper divisors (16499205).

21212955 is a wasteful number, since it uses less digits than its factorization.

21212955 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157147 (or 157141 counting only the distinct ones).

The product of its digits is 1800, while the sum is 27.

The square root of 21212955 is about 4605.7523815333. The cubic root of 21212955 is about 276.8218649893.

The spelling of 21212955 in words is "twenty-one million, two hundred twelve thousand, nine hundred fifty-five".