1620957391 has 4 divisors (see below), whose sum is σ = 1621050784. Its totient is φ = 1620864000.

The previous prime is 1620957379. The next prime is 1620957433. The reversal of 1620957391 is 1937590261.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1620957391 - 2¹⁵ = 1620924623 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1620957311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12135 + ... + 58216.

It is an arithmetic number, because the mean of its divisors is an integer number (405262696).

Almost surely, 2^1620957391 is an apocalyptic number.

1620957391 is a deficient number, since it is larger than the sum of its proper divisors (93393).

1620957391 is an equidigital number, since it uses as much as digits as its factorization.

1620957391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93392.

The product of its (nonzero) digits is 102060, while the sum is 43.

The square root of 1620957391 is about 40261.1151236525. The cubic root of 1620957391 is about 1174.6916084582.

The spelling of 1620957391 in words is "one billion, six hundred twenty million, nine hundred fifty-seven thousand, three hundred ninety-one".