21345427 has 2 divisors, whose sum is σ = 21345428. Its totient is φ = 21345426.

The previous prime is 21345413. The next prime is 21345431. The reversal of 21345427 is 72454312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21345427 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21345395 and 21345404.

It is not a weakly prime, because it can be changed into another prime (21345487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10672713 + 10672714.

It is an arithmetic number, because the mean of its divisors is an integer number (10672714).

Almost surely, 2^21345427 is an apocalyptic number.

21345427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21345427 is an equidigital number, since it uses as much as digits as its factorization.

21345427 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6720, while the sum is 28.

The square root of 21345427 is about 4620.1111458492. Note that the first 4 decimals coincide. The cubic root of 21345427 is about 277.3969078410.

Adding to 21345427 its reverse (72454312), we get a palindrome (93799739).

It can be divided in two parts, 21345 and 427, that multiplied together give a triangular number (9114315 = T₄₂₆₉).

The spelling of 21345427 in words is "twenty-one million, three hundred forty-five thousand, four hundred twenty-seven".