21917039 has 4 divisors (see below), whose sum is σ = 21931080. Its totient is φ = 21903000.

The previous prime is 21917023. The next prime is 21917113. The reversal of 21917039 is 93071912.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21917039 - 2⁴ = 21917023 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21916996 and 21917014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21917339) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4337 + ... + 7914.

It is an arithmetic number, because the mean of its divisors is an integer number (5482770).

Almost surely, 2^21917039 is an apocalyptic number.

21917039 is a deficient number, since it is larger than the sum of its proper divisors (14041).

21917039 is a wasteful number, since it uses less digits than its factorization.

21917039 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14040.

The product of its (nonzero) digits is 3402, while the sum is 32.

The square root of 21917039 is about 4681.5637344802. The cubic root of 21917039 is about 279.8512773121.

The spelling of 21917039 in words is "twenty-one million, nine hundred seventeen thousand, thirty-nine".