20699980 has 48 divisors (see below), whose sum is σ = 49996800. Its totient is φ = 7051968.

The previous prime is 20699947. The next prime is 20699981. The reversal of 20699980 is 8999602.

It is not an unprimeable number, because it can be changed into a prime (20699981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27489 + ... + 28231.

It is an arithmetic number, because the mean of its divisors is an integer number (1041600).

Almost surely, 2^20699980 is an apocalyptic number.

20699980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

20699980 is the 3715-th pentagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20699980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24998400).

20699980 is an abundant number, since it is smaller than the sum of its proper divisors (29296820).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20699980 is a wasteful number, since it uses less digits than its factorization.

20699980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 958 (or 956 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 43.

The square root of 20699980 is about 4549.7230684955. The cubic root of 20699980 is about 274.5722495986.

The spelling of 20699980 in words is "twenty million, six hundred ninety-nine thousand, nine hundred eighty".