21917007 has 16 divisors (see below), whose sum is σ = 37108480. Its totient is φ = 12523896.

The previous prime is 21917003. The next prime is 21917023. The reversal of 21917007 is 70071912.

It is not a de Polignac number, because 21917007 - 2² = 21917003 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21917003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57793 + ... + 58170.

It is an arithmetic number, because the mean of its divisors is an integer number (2319280).

Almost surely, 2^21917007 is an apocalyptic number.

21917007 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21917007 is a deficient number, since it is larger than the sum of its proper divisors (15191473).

21917007 is a wasteful number, since it uses less digits than its factorization.

21917007 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115979 (or 115973 counting only the distinct ones).

The product of its (nonzero) digits is 882, while the sum is 27.

The square root of 21917007 is about 4681.5603168175. The cubic root of 21917007 is about 279.8511411129.

Adding to 21917007 its reverse (70071912), we get a palindrome (91988919).

The spelling of 21917007 in words is "twenty-one million, nine hundred seventeen thousand, seven".