20315981 has 8 divisors (see below), whose sum is σ = 23245824. Its totient is φ = 17393040.

The previous prime is 20315917. The next prime is 20316017. The reversal of 20315981 is 18951302.

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

It is not a de Polignac number, because 20315981 - 2⁶ = 20315917 is a prime.

It is a super-2 number, since 2×20315981² = 825478167984722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20315081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9311 + ... + 11283.

It is an arithmetic number, because the mean of its divisors is an integer number (2905728).

Almost surely, 2^20315981 is an apocalyptic number.

It is an amenable number.

20315981 is a deficient number, since it is larger than the sum of its proper divisors (2929843).

20315981 is a wasteful number, since it uses less digits than its factorization.

20315981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3451.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 20315981 is about 4507.3252600628. The cubic root of 20315981 is about 272.8638060848.

The spelling of 20315981 in words is "twenty million, three hundred fifteen thousand, nine hundred eighty-one".