20505988 has 6 divisors (see below), whose sum is σ = 35885486. Its totient is φ = 10252992.

The previous prime is 20505983. The next prime is 20506001. The reversal of 20505988 is 88950502.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 18249984 + 2256004 = 4272^2 + 1502^2 .

It is a super-2 number, since 2×20505988² = 840991087712288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20505983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2563245 + ... + 2563252.

Almost surely, 2^20505988 is an apocalyptic number.

It is an amenable number.

20505988 is a deficient number, since it is larger than the sum of its proper divisors (15379498).

20505988 is a wasteful number, since it uses less digits than its factorization.

20505988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5126501 (or 5126499 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 37.

The square root of 20505988 is about 4528.3537847655. The cubic root of 20505988 is about 273.7118287373.

The spelling of 20505988 in words is "twenty million, five hundred five thousand, nine hundred eighty-eight".