21771801 has 8 divisors (see below), whose sum is σ = 32254560. Its totient is φ = 14514516.

The previous prime is 21771793. The next prime is 21771809. The reversal of 21771801 is 10817712.

It is an interprime number because it is at equal distance from previous prime (21771793) and next prime (21771809).

It is not a de Polignac number, because 21771801 - 2³ = 21771793 is a prime.

It is a super-2 number, since 2×21771801² = 948022637567202, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 806363 = 21771801 / (2 + 1 + 7 + 7 + 1 + 8 + 0 + 1).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21771809) 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 7 ways as a sum of consecutive naturals, for example, 403155 + ... + 403208.

It is an arithmetic number, because the mean of its divisors is an integer number (4031820).

Almost surely, 2^21771801 is an apocalyptic number.

It is an amenable number.

21771801 is a deficient number, since it is larger than the sum of its proper divisors (10482759).

21771801 is an equidigital number, since it uses as much as digits as its factorization.

21771801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 806372 (or 806366 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 27.

The square root of 21771801 is about 4666.0262536767. The cubic root of 21771801 is about 279.2317417860.

The spelling of 21771801 in words is "twenty-one million, seven hundred seventy-one thousand, eight hundred one".