1621245491 has 2 divisors, whose sum is σ = 1621245492. Its totient is φ = 1621245490.

The previous prime is 1621245421. The next prime is 1621245497. The reversal of 1621245491 is 1945421261.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1621245491 - 2¹⁴ = 1621229107 is a prime.

It is not a weakly prime, because it can be changed into another prime (1621245497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810622745 + 810622746.

It is an arithmetic number, because the mean of its divisors is an integer number (810622746).

Almost surely, 2^1621245491 is an apocalyptic number.

1621245491 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621245491 is an equidigital number, since it uses as much as digits as its factorization.

1621245491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 35.

The square root of 1621245491 is about 40264.6928586324. The cubic root of 1621245491 is about 1174.7611987317.

The spelling of 1621245491 in words is "one billion, six hundred twenty-one million, two hundred forty-five thousand, four hundred ninety-one".