1621403453 has 4 divisors (see below), whose sum is σ = 1622662620. Its totient is φ = 1620144288.

The previous prime is 1621403419. The next prime is 1621403461. The reversal of 1621403453 is 3543041261.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3543041261 = 733 ⋅4833617.

It can be written as a sum of positive squares in 2 ways, for example, as 1247290489 + 374112964 = 35317^2 + 19342^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621403453 - 2⁶ = 1621403389 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 (1621403053) 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, 627650 + ... + 630227.

It is an arithmetic number, because the mean of its divisors is an integer number (405665655).

Almost surely, 2^1621403453 is an apocalyptic number.

It is an amenable number.

1621403453 is a deficient number, since it is larger than the sum of its proper divisors (1259167).

1621403453 is a wasteful number, since it uses less digits than its factorization.

1621403453 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1259166.

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 1621403453 is about 40266.6543556824. The cubic root of 1621403453 is about 1174.7993507991.

The spelling of 1621403453 in words is "one billion, six hundred twenty-one million, four hundred three thousand, four hundred fifty-three".