20829987 has 8 divisors (see below), whose sum is σ = 30859280. Its totient is φ = 13886640.

The previous prime is 20829983. The next prime is 20829989. The reversal of 20829987 is 78992802.

It is not a de Polignac number, because 20829987 - 2² = 20829983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20829983) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 385714 + ... + 385767.

It is an arithmetic number, because the mean of its divisors is an integer number (3857410).

Almost surely, 2^20829987 is an apocalyptic number.

20829987 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

20829987 is a deficient number, since it is larger than the sum of its proper divisors (10029293).

20829987 is an equidigital number, since it uses as much as digits as its factorization.

20829987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 771490 (or 771484 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 45.

The square root of 20829987 is about 4563.9880587048. The cubic root of 20829987 is about 275.1458708201.

The spelling of 20829987 in words is "twenty million, eight hundred twenty-nine thousand, nine hundred eighty-seven".