20521631 has 8 divisors (see below), whose sum is σ = 22431024. Its totient is φ = 18659520.

The previous prime is 20521609. The next prime is 20521639. The reversal of 20521631 is 13612502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20521631 is a prime.

It is a super-2 number, since 2×20521631² = 842274677800322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20521639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10910 + ... + 12651.

It is an arithmetic number, because the mean of its divisors is an integer number (2803878).

Almost surely, 2^20521631 is an apocalyptic number.

20521631 is a deficient number, since it is larger than the sum of its proper divisors (1909393).

20521631 is a wasteful number, since it uses less digits than its factorization.

20521631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23641.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 20521631 is about 4530.0806836082. The cubic root of 20521631 is about 273.7814114342.

The spelling of 20521631 in words is "twenty million, five hundred twenty-one thousand, six hundred thirty-one".