21802457 has 2 divisors, whose sum is σ = 21802458. Its totient is φ = 21802456.

The previous prime is 21802453. The next prime is 21802463. The reversal of 21802457 is 75420812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11999296 + 9803161 = 3464^2 + 3131^2 .

It is a cyclic number.

It is not a de Polignac number, because 21802457 - 2² = 21802453 is a prime.

It is not a weakly prime, because it can be changed into another prime (21802453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10901228 + 10901229.

It is an arithmetic number, because the mean of its divisors is an integer number (10901229).

Almost surely, 2^21802457 is an apocalyptic number.

It is an amenable number.

21802457 is a deficient number, since it is larger than the sum of its proper divisors (1).

21802457 is an equidigital number, since it uses as much as digits as its factorization.

21802457 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4480, while the sum is 29.

The square root of 21802457 is about 4669.3101203497. The cubic root of 21802457 is about 279.3627386611.

The spelling of 21802457 in words is "twenty-one million, eight hundred two thousand, four hundred fifty-seven".