21054457 has 2 divisors, whose sum is σ = 21054458. Its totient is φ = 21054456.

The previous prime is 21054437. The next prime is 21054521. The reversal of 21054457 is 75445012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19105641 + 1948816 = 4371^2 + 1396^2 .

It is a cyclic number.

It is not a de Polignac number, because 21054457 - 2⁷ = 21054329 is a prime.

It is not a weakly prime, because it can be changed into another prime (21054427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10527228 + 10527229.

It is an arithmetic number, because the mean of its divisors is an integer number (10527229).

Almost surely, 2^21054457 is an apocalyptic number.

It is an amenable number.

21054457 is a deficient number, since it is larger than the sum of its proper divisors (1).

21054457 is an equidigital number, since it uses as much as digits as its factorization.

21054457 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5600, while the sum is 28.

The square root of 21054457 is about 4588.5135937469. The cubic root of 21054457 is about 276.1306923227.

Adding to 21054457 its reverse (75445012), we get a palindrome (96499469).

The spelling of 21054457 in words is "twenty-one million, fifty-four thousand, four hundred fifty-seven".