21965247 has 12 divisors (see below), whose sum is σ = 31831800. Its totient is φ = 14595408.

The previous prime is 21965243. The next prime is 21965249. The reversal of 21965247 is 74256912.

It is not a de Polignac number, because 21965247 - 2² = 21965243 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21965243) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 997 + ... + 6702.

It is an arithmetic number, because the mean of its divisors is an integer number (2652650).

Almost surely, 2^21965247 is an apocalyptic number.

21965247 is a deficient number, since it is larger than the sum of its proper divisors (9866553).

21965247 is a wasteful number, since it uses less digits than its factorization.

21965247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8022 (or 8019 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 21965247 is about 4686.7096133642. The cubic root of 21965247 is about 280.0563109534.

The spelling of 21965247 in words is "twenty-one million, nine hundred sixty-five thousand, two hundred forty-seven".