21890629 has 2 divisors, whose sum is σ = 21890630. Its totient is φ = 21890628.

The previous prime is 21890623. The next prime is 21890647. The reversal of 21890629 is 92609812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19936225 + 1954404 = 4465^2 + 1398^2 .

It is a cyclic number.

It is not a de Polignac number, because 21890629 - 2¹⁷ = 21759557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21890623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10945314 + 10945315.

It is an arithmetic number, because the mean of its divisors is an integer number (10945315).

Almost surely, 2^21890629 is an apocalyptic number.

It is an amenable number.

21890629 is a deficient number, since it is larger than the sum of its proper divisors (1).

21890629 is an equidigital number, since it uses as much as digits as its factorization.

21890629 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 21890629 is about 4678.7422455186. The cubic root of 21890629 is about 279.7388253383.

The spelling of 21890629 in words is "twenty-one million, eight hundred ninety thousand, six hundred twenty-nine".