21917477 has 2 divisors, whose sum is σ = 21917478. Its totient is φ = 21917476.

The previous prime is 21917443. The next prime is 21917491. The reversal of 21917477 is 77471912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11874916 + 10042561 = 3446^2 + 3169^2 .

It is a cyclic number.

It is not a de Polignac number, because 21917477 - 2⁸ = 21917221 is a prime.

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 21917477.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21917177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10958738 + 10958739.

It is an arithmetic number, because the mean of its divisors is an integer number (10958739).

Almost surely, 2^21917477 is an apocalyptic number.

It is an amenable number.

21917477 is a deficient number, since it is larger than the sum of its proper divisors (1).

21917477 is an equidigital number, since it uses as much as digits as its factorization.

21917477 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24696, while the sum is 38.

The square root of 21917477 is about 4681.6105134879. The cubic root of 21917477 is about 279.8531415244.

The spelling of 21917477 in words is "twenty-one million, nine hundred seventeen thousand, four hundred seventy-seven".