21770531 has 2 divisors, whose sum is σ = 21770532. Its totient is φ = 21770530.

The previous prime is 21770521. The next prime is 21770543. The reversal of 21770531 is 13507712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21770531 - 2²² = 17576227 is a prime.

It is a super-2 number, since 2×21770531² = 947912040043922, which contains 22 as substring.

It is a Chen prime.

It is a zygodrome in base 3.

It is a self number, because there is not a number n which added to its sum of digits gives 21770531.

It is not a weakly prime, because it can be changed into another prime (21770521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885265 + 10885266.

It is an arithmetic number, because the mean of its divisors is an integer number (10885266).

Almost surely, 2^21770531 is an apocalyptic number.

21770531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21770531 is an equidigital number, since it uses as much as digits as its factorization.

21770531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1470, while the sum is 26.

The square root of 21770531 is about 4665.8901615876. The cubic root of 21770531 is about 279.2263122672.

The spelling of 21770531 in words is "twenty-one million, seven hundred seventy thousand, five hundred thirty-one".