21420677 has 2 divisors, whose sum is σ = 21420678. Its totient is φ = 21420676.

The previous prime is 21420667. The next prime is 21420683. The reversal of 21420677 is 77602412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21077281 + 343396 = 4591^2 + 586^2 .

It is a cyclic number.

It is not a de Polignac number, because 21420677 - 2⁴ = 21420661 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21420667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710338 + 10710339.

It is an arithmetic number, because the mean of its divisors is an integer number (10710339).

Almost surely, 2^21420677 is an apocalyptic number.

It is an amenable number.

21420677 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420677 is an equidigital number, since it uses as much as digits as its factorization.

21420677 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4704, while the sum is 29.

The square root of 21420677 is about 4628.2477245714. The cubic root of 21420677 is about 277.7224988252.

The spelling of 21420677 in words is "twenty-one million, four hundred twenty thousand, six hundred seventy-seven".