21236947 has 2 divisors, whose sum is σ = 21236948. Its totient is φ = 21236946.

The previous prime is 21236921. The next prime is 21236951. The reversal of 21236947 is 74963212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21236947 - 2⁷ = 21236819 is a prime.

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

It is not a weakly prime, because it can be changed into another prime (21236447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10618473 + 10618474.

It is an arithmetic number, because the mean of its divisors is an integer number (10618474).

Almost surely, 2^21236947 is an apocalyptic number.

21236947 is a deficient number, since it is larger than the sum of its proper divisors (1).

21236947 is an equidigital number, since it uses as much as digits as its factorization.

21236947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 34.

The square root of 21236947 is about 4608.3562145303. The cubic root of 21236947 is about 276.9261881555.

The spelling of 21236947 in words is "twenty-one million, two hundred thirty-six thousand, nine hundred forty-seven".