1657421 has 2 divisors, whose sum is σ = 1657422. Its totient is φ = 1657420.

The previous prime is 1657399. The next prime is 1657429. The reversal of 1657421 is 1247561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1612900 + 44521 = 1270^2 + 211^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1657421 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 (1657429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 828710 + 828711.

It is an arithmetic number, because the mean of its divisors is an integer number (828711).

2^1657421 is an apocalyptic number.

It is an amenable number.

1657421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1657421 is an equidigital number, since it uses as much as digits as its factorization.

1657421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1680, while the sum is 26.

The square root of 1657421 is about 1287.4086375351. The cubic root of 1657421 is about 118.3434644944.

The spelling of 1657421 in words is "one million, six hundred fifty-seven thousand, four hundred twenty-one".