21771619 has 2 divisors, whose sum is σ = 21771620. Its totient is φ = 21771618.

The previous prime is 21771557. The next prime is 21771671. The reversal of 21771619 is 91617712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21771619 - 2¹⁷ = 21640547 is a prime.

It is a super-2 number, since 2×21771619² = 948006787762322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21771019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885809 + 10885810.

It is an arithmetic number, because the mean of its divisors is an integer number (10885810).

Almost surely, 2^21771619 is an apocalyptic number.

21771619 is a deficient number, since it is larger than the sum of its proper divisors (1).

21771619 is an equidigital number, since it uses as much as digits as its factorization.

21771619 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5292, while the sum is 34.

The square root of 21771619 is about 4666.0067509595. The cubic root of 21771619 is about 279.2309637104.

The spelling of 21771619 in words is "twenty-one million, seven hundred seventy-one thousand, six hundred nineteen".