21771207 has 48 divisors (see below), whose sum is σ = 36019200. Its totient is φ = 12947040.

The previous prime is 21771187. The next prime is 21771221. The reversal of 21771207 is 70217712.

It is not a de Polignac number, because 21771207 - 2¹⁴ = 21754823 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21771247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 588393 + ... + 588429.

It is an arithmetic number, because the mean of its divisors is an integer number (750400).

Almost surely, 2^21771207 is an apocalyptic number.

21771207 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21771207 is a deficient number, since it is larger than the sum of its proper divisors (14247993).

21771207 is a wasteful number, since it uses less digits than its factorization.

21771207 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133 (or 90 counting only the distinct ones).

The product of its (nonzero) digits is 1372, while the sum is 27.

The square root of 21771207 is about 4665.9626016504. The cubic root of 21771207 is about 279.2292023366.

Adding to 21771207 its reverse (70217712), we get a palindrome (91988919).

The spelling of 21771207 in words is "twenty-one million, seven hundred seventy-one thousand, two hundred seven".