21461669 has 2 divisors, whose sum is σ = 21461670. Its totient is φ = 21461668.

The previous prime is 21461647. The next prime is 21461677. The reversal of 21461669 is 96616412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12159169 + 9302500 = 3487^2 + 3050^2 .

It is a cyclic number.

It is not a de Polignac number, because 21461669 - 2⁸ = 21461413 is a prime.

It is a super-2 number, since 2×21461669² = 921206472531122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21461969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10730834 + 10730835.

It is an arithmetic number, because the mean of its divisors is an integer number (10730835).

Almost surely, 2^21461669 is an apocalyptic number.

It is an amenable number.

21461669 is a deficient number, since it is larger than the sum of its proper divisors (1).

21461669 is an equidigital number, since it uses as much as digits as its factorization.

21461669 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 35.

The square root of 21461669 is about 4632.6740658069. The cubic root of 21461669 is about 277.8995418820.

The spelling of 21461669 in words is "twenty-one million, four hundred sixty-one thousand, six hundred sixty-nine".