21780072085 has 16 divisors (see below), whose sum is σ = 26485482240. Its totient is φ = 17191437120.

The previous prime is 21780072071. The next prime is 21780072131. The reversal of 21780072085 is 58027008712.

It is not a de Polignac number, because 21780072085 - 2¹⁵ = 21780039317 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 567195 + ... + 604375.

It is an arithmetic number, because the mean of its divisors is an integer number (1655342640).

Almost surely, 2^21780072085 is an apocalyptic number.

It is an amenable number.

21780072085 is a deficient number, since it is larger than the sum of its proper divisors (4705410155).

21780072085 is a wasteful number, since it uses less digits than its factorization.

21780072085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38748.

The product of its (nonzero) digits is 62720, while the sum is 40.

The spelling of 21780072085 in words is "twenty-one billion, seven hundred eighty million, seventy-two thousand, eighty-five".