21670337 has 16 divisors (see below), whose sum is σ = 24675840. Its totient is φ = 18887232.

The previous prime is 21670331. The next prime is 21670339. The reversal of 21670337 is 73307612.

It is not a de Polignac number, because 21670337 - 2⁴ = 21670321 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21670331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17108 + ... + 18330.

It is an arithmetic number, because the mean of its divisors is an integer number (1542240).

Almost surely, 2^21670337 is an apocalyptic number.

It is an amenable number.

21670337 is a deficient number, since it is larger than the sum of its proper divisors (3005503).

21670337 is a wasteful number, since it uses less digits than its factorization.

21670337 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1312.

The product of its (nonzero) digits is 5292, while the sum is 29.

The square root of 21670337 is about 4655.1409216048. The cubic root of 21670337 is about 278.7972945552.

21670337 divided by its sum of digits (29) gives a triangular number (747253 = T₁₂₂₂).

Adding to 21670337 its reverse (73307612), we get a palindrome (94977949).

The spelling of 21670337 in words is "twenty-one million, six hundred seventy thousand, three hundred thirty-seven".