1721257541 has 2 divisors, whose sum is σ = 1721257542. Its totient is φ = 1721257540.

The previous prime is 1721257529. The next prime is 1721257673. The reversal of 1721257541 is 1457521271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1589696641 + 131560900 = 39871^2 + 11470^2 .

It is a cyclic number.

It is not a de Polignac number, because 1721257541 - 2¹⁴ = 1721241157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1721257511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860628770 + 860628771.

It is an arithmetic number, because the mean of its divisors is an integer number (860628771).

Almost surely, 2^1721257541 is an apocalyptic number.

It is an amenable number.

1721257541 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721257541 is an equidigital number, since it uses as much as digits as its factorization.

1721257541 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19600, while the sum is 35.

The square root of 1721257541 is about 41488.0409395286. The cubic root of 1721257541 is about 1198.4372112281.

The spelling of 1721257541 in words is "one billion, seven hundred twenty-one million, two hundred fifty-seven thousand, five hundred forty-one".