20515680 has 120 divisors (see below), whose sum is σ = 72448992. Its totient is φ = 5467392.

The previous prime is 20515679. The next prime is 20515699. The reversal of 20515680 is 8651502.

It is a tau number, because it is divible by the number of its divisors (120).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 12169 + ... + 13751.

Almost surely, 2^20515680 is an apocalyptic number.

20515680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20515680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36224496).

20515680 is an abundant number, since it is smaller than the sum of its proper divisors (51933312).

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

20515680 is a wasteful number, since it uses less digits than its factorization.

20515680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1610 (or 1593 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The square root of 20515680 is about 4529.4238044149. The cubic root of 20515680 is about 273.7549445532.

The spelling of 20515680 in words is "twenty million, five hundred fifteen thousand, six hundred eighty".