21549677 has 2 divisors, whose sum is σ = 21549678. Its totient is φ = 21549676.

The previous prime is 21549637. The next prime is 21549701. The reversal of 21549677 is 77694512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12823561 + 8726116 = 3581^2 + 2954^2 .

It is a cyclic number.

It is not a de Polignac number, because 21549677 - 2⁶ = 21549613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21549637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10774838 + 10774839.

It is an arithmetic number, because the mean of its divisors is an integer number (10774839).

Almost surely, 2^21549677 is an apocalyptic number.

It is an amenable number.

21549677 is a deficient number, since it is larger than the sum of its proper divisors (1).

21549677 is an equidigital number, since it uses as much as digits as its factorization.

21549677 is an evil number, because the sum of its binary digits is even.

The product of its digits is 105840, while the sum is 41.

The square root of 21549677 is about 4642.1629656874. The cubic root of 21549677 is about 278.2788852901.

The spelling of 21549677 in words is "twenty-one million, five hundred forty-nine thousand, six hundred seventy-seven".