20521603 has 2 divisors, whose sum is σ = 20521604. Its totient is φ = 20521602.

The previous prime is 20521583. The next prime is 20521609. The reversal of 20521603 is 30612502.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20521603 - 2²¹ = 18424451 is a prime.

It is a super-2 number, since 2×20521603² = 842272379379218, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20521609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10260801 + 10260802.

It is an arithmetic number, because the mean of its divisors is an integer number (10260802).

Almost surely, 2^20521603 is an apocalyptic number.

20521603 is a deficient number, since it is larger than the sum of its proper divisors (1).

20521603 is an equidigital number, since it uses as much as digits as its factorization.

20521603 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 20521603 is about 4530.0775931544. The cubic root of 20521603 is about 273.7812869170.

It can be divided in two parts, 2052 and 1603, that added together give a triangular number (3655 = T₈₅).

The spelling of 20521603 in words is "twenty million, five hundred twenty-one thousand, six hundred three".