21193237 has 12 divisors (see below), whose sum is σ = 24249316. Its totient is φ = 18408960.

The previous prime is 21193231. The next prime is 21193247. The reversal of 21193237 is 73239112.

It can be written as a sum of positive squares in 6 ways, for example, as 3837681 + 17355556 = 1959^2 + 4166^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21193237 is a prime.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21193231) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 937 + ... + 6577.

Almost surely, 2^21193237 is an apocalyptic number.

It is an amenable number.

21193237 is a deficient number, since it is larger than the sum of its proper divisors (3056079).

21193237 is a wasteful number, since it uses less digits than its factorization.

21193237 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5688 (or 5671 counting only the distinct ones).

The product of its digits is 2268, while the sum is 28.

The square root of 21193237 is about 4603.6112998384. The cubic root of 21193237 is about 276.7360673303.

It can be divided in two parts, 2119 and 3237, that added together give a triangular number (5356 = T₁₀₃).

The spelling of 21193237 in words is "twenty-one million, one hundred ninety-three thousand, two hundred thirty-seven".