21662447 has 2 divisors, whose sum is σ = 21662448. Its totient is φ = 21662446.

The previous prime is 21662393. The next prime is 21662453. The reversal of 21662447 is 74426612.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21662447 is a prime.

It is a super-2 number, since 2×21662447² = 938523220055618, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21662467) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10831223 + 10831224.

It is an arithmetic number, because the mean of its divisors is an integer number (10831224).

Almost surely, 2^21662447 is an apocalyptic number.

21662447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21662447 is an equidigital number, since it uses as much as digits as its factorization.

21662447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16128, while the sum is 32.

The square root of 21662447 is about 4654.2933942759. The cubic root of 21662447 is about 278.7634544774.

It can be divided in two parts, 216624 and 47, that multiplied together give a triangular number (10181328 = T₄₅₁₂).

The spelling of 21662447 in words is "twenty-one million, six hundred sixty-two thousand, four hundred forty-seven".