21506380389 has 24 divisors (see below), whose sum is σ = 34693425312. Its totient is φ = 13234693680.

The previous prime is 21506380373. The next prime is 21506380453. The reversal of 21506380389 is 98308360512.

It is a happy number.

21506380389 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 638 + 0 + 3 + 8 + 9 = 666.

It is not a de Polignac number, because 21506380389 - 2⁴ = 21506380373 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21506380369) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3400827 + ... + 3407144.

It is an arithmetic number, because the mean of its divisors is an integer number (1445559388).

Almost surely, 2^21506380389 is an apocalyptic number.

It is an amenable number.

21506380389 is a deficient number, since it is larger than the sum of its proper divisors (13187044923).

21506380389 is an equidigital number, since it uses as much as digits as its factorization.

21506380389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6807999 (or 6807987 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 45.

The spelling of 21506380389 in words is "twenty-one billion, five hundred six million, three hundred eighty thousand, three hundred eighty-nine".