20399287 has 4 divisors (see below), whose sum is σ = 20524600. Its totient is φ = 20273976.

The previous prime is 20399279. The next prime is 20399299. The reversal of 20399287 is 78299302.

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 20399287 - 2³ = 20399279 is a prime.

It is a super-2 number, since 2×20399287² = 832261820216738, 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 (20399227) 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, 62412 + ... + 62737.

It is an arithmetic number, because the mean of its divisors is an integer number (5131150).

Almost surely, 2^20399287 is an apocalyptic number.

20399287 is a deficient number, since it is larger than the sum of its proper divisors (125313).

20399287 is a wasteful number, since it uses less digits than its factorization.

20399287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125312.

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 20399287 is about 4516.5569851381. The cubic root of 20399287 is about 273.2362582436.

The spelling of 20399287 in words is "twenty million, three hundred ninety-nine thousand, two hundred eighty-seven".