21154252749 has 8 divisors (see below), whose sum is σ = 32235051840. Its totient is φ = 12088144416.

The previous prime is 21154252727. The next prime is 21154252759. The reversal of 21154252749 is 94725245112.

It is a happy number.

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

It is not a de Polignac number, because 21154252749 - 2¹³ = 21154244557 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21154252749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21154252759) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 503672664 + ... + 503672705.

It is an arithmetic number, because the mean of its divisors is an integer number (4029381480).

Almost surely, 2^21154252749 is an apocalyptic number.

It is an amenable number.

21154252749 is a deficient number, since it is larger than the sum of its proper divisors (11080799091).

21154252749 is a wasteful number, since it uses less digits than its factorization.

21154252749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1007345379.

The product of its digits is 201600, while the sum is 42.

The spelling of 21154252749 in words is "twenty-one billion, one hundred fifty-four million, two hundred fifty-two thousand, seven hundred forty-nine".