21277749251 has 16 divisors (see below), whose sum is σ = 23666162688. Its totient is φ = 18965512800.

The previous prime is 21277749197. The next prime is 21277749271. The reversal of 21277749251 is 15294777212.

It is a cyclic number.

It is not a de Polignac number, because 21277749251 - 2¹⁰ = 21277748227 is a prime.

It is a super-2 number, since 2×21277749251² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21277749196 and 21277749205.

It is not an unprimeable number, because it can be changed into a prime (21277749271) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 901916 + ... + 925206.

It is an arithmetic number, because the mean of its divisors is an integer number (1479135168).

Almost surely, 2^21277749251 is an apocalyptic number.

21277749251 is a deficient number, since it is larger than the sum of its proper divisors (2388413437).

21277749251 is a wasteful number, since it uses less digits than its factorization.

21277749251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24922.

The product of its digits is 493920, while the sum is 47.

The spelling of 21277749251 in words is "twenty-one billion, two hundred seventy-seven million, seven hundred forty-nine thousand, two hundred fifty-one".