15781408921 has 8 divisors (see below), whose sum is σ = 15941971584. Its totient is φ = 15621088560.

The previous prime is 15781408861. The next prime is 15781408927. The reversal of 15781408921 is 12980418751.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 15781408921 - 2¹¹ = 15781406873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15781408927) 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, 71811 + ... + 191623.

It is an arithmetic number, because the mean of its divisors is an integer number (1992746448).

Almost surely, 2^15781408921 is an apocalyptic number.

It is an amenable number.

15781408921 is a deficient number, since it is larger than the sum of its proper divisors (160562663).

15781408921 is a wasteful number, since it uses less digits than its factorization.

15781408921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121151.

The product of its (nonzero) digits is 161280, while the sum is 46.

The spelling of 15781408921 in words is "fifteen billion, seven hundred eighty-one million, four hundred eight thousand, nine hundred twenty-one".