21277457 has 2 divisors, whose sum is σ = 21277458. Its totient is φ = 21277456.

The previous prime is 21277441. The next prime is 21277469. The reversal of 21277457 is 75477212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12988816 + 8288641 = 3604^2 + 2879^2 .

It is a cyclic number.

It is not a de Polignac number, because 21277457 - 2⁴ = 21277441 is a prime.

It is not a weakly prime, because it can be changed into another prime (21277657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10638728 + 10638729.

It is an arithmetic number, because the mean of its divisors is an integer number (10638729).

Almost surely, 2^21277457 is an apocalyptic number.

It is an amenable number.

21277457 is a deficient number, since it is larger than the sum of its proper divisors (1).

21277457 is an equidigital number, since it uses as much as digits as its factorization.

21277457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27440, while the sum is 35.

The square root of 21277457 is about 4612.7493970516. The cubic root of 21277457 is about 277.1021574915.

The spelling of 21277457 in words is "twenty-one million, two hundred seventy-seven thousand, four hundred fifty-seven".