21193251 has 16 divisors (see below), whose sum is σ = 28815360. Its totient is φ = 13852800.

The previous prime is 21193247. The next prime is 21193253. The reversal of 21193251 is 15239112.

It is not a de Polignac number, because 21193251 - 2² = 21193247 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21193253) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52651 + ... + 53051.

It is an arithmetic number, because the mean of its divisors is an integer number (1800960).

Almost surely, 2^21193251 is an apocalyptic number.

21193251 is a deficient number, since it is larger than the sum of its proper divisors (7622109).

21193251 is a wasteful number, since it uses less digits than its factorization.

21193251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 706.

The product of its digits is 540, while the sum is 24.

The square root of 21193251 is about 4603.6128203836. The cubic root of 21193251 is about 276.7361282664.

The spelling of 21193251 in words is "twenty-one million, one hundred ninety-three thousand, two hundred fifty-one".