21012001272 has 48 divisors (see below), whose sum is σ = 58869837000. Its totient is φ = 6762482496.

The previous prime is 21012001259. The next prime is 21012001273. The reversal of 21012001272 is 27210021012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012001273) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5029522 + ... + 5033697.

Almost surely, 2^21012001272 is an apocalyptic number.

It is an amenable number.

21012001272 is an abundant number, since it is smaller than the sum of its proper divisors (37857835728).

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

21012001272 is a wasteful number, since it uses less digits than its factorization.

21012001272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10063260 (or 10063253 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

Adding to 21012001272 its reverse (27210021012), we get a palindrome (48222022284).

The spelling of 21012001272 in words is "twenty-one billion, twelve million, one thousand, two hundred seventy-two".