21501871378 has 8 divisors (see below), whose sum is σ = 34733792268. Its totient is φ = 9923940624.

The previous prime is 21501871253. The next prime is 21501871423. The reversal of 21501871378 is 87317810512.

It can be written as a sum of positive squares in 2 ways, for example, as 16905980529 + 4595890849 = 130023^2 + 67793^2 .

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, 413497501 + ... + 413497552.

Almost surely, 2^21501871378 is an apocalyptic number.

21501871378 is a deficient number, since it is larger than the sum of its proper divisors (13231920890).

21501871378 is a wasteful number, since it uses less digits than its factorization.

21501871378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 826995068.

The product of its (nonzero) digits is 94080, while the sum is 43.

The spelling of 21501871378 in words is "twenty-one billion, five hundred one million, eight hundred seventy-one thousand, three hundred seventy-eight".