21001678812 has 24 divisors (see below), whose sum is σ = 54448797200. Its totient is φ = 7000559568.

The previous prime is 21001678801. The next prime is 21001678813. The reversal of 21001678812 is 21887610012.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001678813) 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, 97229887 + ... + 97230102.

Almost surely, 2^21001678812 is an apocalyptic number.

It is an amenable number.

21001678812 is an abundant number, since it is smaller than the sum of its proper divisors (33447118388).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21001678812 is a wasteful number, since it uses less digits than its factorization.

21001678812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194460002 (or 194459994 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The spelling of 21001678812 in words is "twenty-one billion, one million, six hundred seventy-eight thousand, eight hundred twelve".