21491916610 has 8 divisors (see below), whose sum is σ = 38685449916. Its totient is φ = 8596766640.

The previous prime is 21491916577. The next prime is 21491916643. The reversal of 21491916610 is 1661919412.

It is an interprime number because it is at equal distance from previous prime (21491916577) and next prime (21491916643).

It can be written as a sum of positive squares in 2 ways, for example, as 21486575889 + 5340721 = 146583^2 + 2311^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1074595821 + ... + 1074595840.

Almost surely, 2^21491916610 is an apocalyptic number.

21491916610 is a deficient number, since it is larger than the sum of its proper divisors (17193533306).

21491916610 is a wasteful number, since it uses less digits than its factorization.

21491916610 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2149191668.

The product of its (nonzero) digits is 23328, while the sum is 40.

The spelling of 21491916610 in words is "twenty-one billion, four hundred ninety-one million, nine hundred sixteen thousand, six hundred ten".