1621368553 has 16 divisors (see below), whose sum is σ = 1959301120. Its totient is φ = 1310672016.

The previous prime is 1621368547. The next prime is 1621368571. The reversal of 1621368553 is 3558631261.

It is a cyclic number.

It is not a de Polignac number, because 1621368553 - 2¹³ = 1621360361 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1621368503) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2326 + ... + 56992.

It is an arithmetic number, because the mean of its divisors is an integer number (122456320).

Almost surely, 2^1621368553 is an apocalyptic number.

It is an amenable number.

1621368553 is a deficient number, since it is larger than the sum of its proper divisors (337932567).

1621368553 is a wasteful number, since it uses less digits than its factorization.

1621368553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54916.

The product of its digits is 129600, while the sum is 40.

The square root of 1621368553 is about 40266.2209922908. The cubic root of 1621368553 is about 1174.7909217246.

The spelling of 1621368553 in words is "one billion, six hundred twenty-one million, three hundred sixty-eight thousand, five hundred fifty-three".