21236949 has 6 divisors (see below), whose sum is σ = 30675606. Its totient is φ = 14157960.

The previous prime is 21236947. The next prime is 21236951. The reversal of 21236949 is 94963212.

It is an interprime number because it is at equal distance from previous prime (21236947) and next prime (21236951).

It can be written as a sum of positive squares in only one way, i.e., 15563025 + 5673924 = 3945^2 + 2382^2 .

It is not a de Polignac number, because 21236949 - 2¹ = 21236947 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21236947) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1179822 + ... + 1179839.

It is an arithmetic number, because the mean of its divisors is an integer number (5112601).

Almost surely, 2^21236949 is an apocalyptic number.

It is an amenable number.

21236949 is a deficient number, since it is larger than the sum of its proper divisors (9438657).

21236949 is a wasteful number, since it uses less digits than its factorization.

21236949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2359667 (or 2359664 counting only the distinct ones).

The product of its digits is 23328, while the sum is 36.

The square root of 21236949 is about 4608.3564315274. The cubic root of 21236949 is about 276.9261968488.

The spelling of 21236949 in words is "twenty-one million, two hundred thirty-six thousand, nine hundred forty-nine".