20403987 has 4 divisors (see below), whose sum is σ = 27205320. Its totient is φ = 13602656.

The previous prime is 20403959. The next prime is 20403989. The reversal of 20403987 is 78930402.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20403987 - 2⁸ = 20403731 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20403989) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3400662 + ... + 3400667.

It is an arithmetic number, because the mean of its divisors is an integer number (6801330).

Almost surely, 2^20403987 is an apocalyptic number.

20403987 is a deficient number, since it is larger than the sum of its proper divisors (6801333).

20403987 is an equidigital number, since it uses as much as digits as its factorization.

20403987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6801332.

The product of its (nonzero) digits is 12096, while the sum is 33.

The square root of 20403987 is about 4517.0772630098. The cubic root of 20403987 is about 273.2572411959.

The spelling of 20403987 in words is "twenty million, four hundred three thousand, nine hundred eighty-seven".