18878721025 has 12 divisors (see below), whose sum is σ = 23483471292. Its totient is φ = 15055327040.

The previous prime is 18878721007. The next prime is 18878721053. The reversal of 18878721025 is 52012787881.

It can be written as a sum of positive squares in 6 ways, for example, as 5170760464 + 13707960561 = 71908^2 + 117081^2 .

It is not a de Polignac number, because 18878721025 - 2¹³ = 18878712833 is a prime.

It is a super-2 number, since 2×18878721025² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18878721025.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1183162 + ... + 1199011.

It is an arithmetic number, because the mean of its divisors is an integer number (1956955941).

Almost surely, 2^18878721025 is an apocalyptic number.

It is an amenable number.

18878721025 is a deficient number, since it is larger than the sum of its proper divisors (4604750267).

18878721025 is a wasteful number, since it uses less digits than its factorization.

18878721025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2382500 (or 2382495 counting only the distinct ones).

The product of its (nonzero) digits is 501760, while the sum is 49.

The spelling of 18878721025 in words is "eighteen billion, eight hundred seventy-eight million, seven hundred twenty-one thousand, twenty-five".