21770731 has 2 divisors, whose sum is σ = 21770732. Its totient is φ = 21770730.

The previous prime is 21770701. The next prime is 21770747. The reversal of 21770731 is 13707712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21770731 - 2⁷ = 21770603 is a prime.

It is a super-2 number, since 2×21770731² = 947929456548722, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21770731.

It is not a weakly prime, because it can be changed into another prime (21770701) 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 as a sum of consecutive naturals, namely, 10885365 + 10885366.

It is an arithmetic number, because the mean of its divisors is an integer number (10885366).

Almost surely, 2^21770731 is an apocalyptic number.

21770731 is a deficient number, since it is larger than the sum of its proper divisors (1).

21770731 is an equidigital number, since it uses as much as digits as its factorization.

21770731 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2058, while the sum is 28.

The square root of 21770731 is about 4665.9115936760. The cubic root of 21770731 is about 279.2271673236.

The spelling of 21770731 in words is "twenty-one million, seven hundred seventy thousand, seven hundred thirty-one".