21436931 has 2 divisors, whose sum is σ = 21436932. Its totient is φ = 21436930.

The previous prime is 21436927. The next prime is 21436939. The reversal of 21436931 is 13963412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21436931 - 2² = 21436927 is a prime.

It is a super-2 number, since 2×21436931² = 919084021397522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21436894 and 21436903.

It is not a weakly prime, because it can be changed into another prime (21436939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10718465 + 10718466.

It is an arithmetic number, because the mean of its divisors is an integer number (10718466).

Almost surely, 2^21436931 is an apocalyptic number.

21436931 is a deficient number, since it is larger than the sum of its proper divisors (1).

21436931 is an equidigital number, since it uses as much as digits as its factorization.

21436931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 29.

The square root of 21436931 is about 4630.0033477310. The cubic root of 21436931 is about 277.7927263007.

The spelling of 21436931 in words is "twenty-one million, four hundred thirty-six thousand, nine hundred thirty-one".