1621473817 has 4 divisors (see below), whose sum is σ = 1673779456. Its totient is φ = 1569168180.

The previous prime is 1621473811. The next prime is 1621473857. The reversal of 1621473817 is 7183741261.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1621473817 - 2¹⁵ = 1621441049 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1621473817.

It is not an unprimeable number, because it can be changed into a prime (1621473811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26152773 + ... + 26152834.

It is an arithmetic number, because the mean of its divisors is an integer number (418444864).

Almost surely, 2^1621473817 is an apocalyptic number.

It is an amenable number.

1621473817 is a deficient number, since it is larger than the sum of its proper divisors (52305639).

1621473817 is an equidigital number, since it uses as much as digits as its factorization.

1621473817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52305638.

The product of its digits is 56448, while the sum is 40.

The square root of 1621473817 is about 40267.5280716361. The cubic root of 1621473817 is about 1174.8163447981.

The spelling of 1621473817 in words is "one billion, six hundred twenty-one million, four hundred seventy-three thousand, eight hundred seventeen".