20515400218 has 4 divisors (see below), whose sum is σ = 30773100330. Its totient is φ = 10257700108.

The previous prime is 20515400203. The next prime is 20515400231. The reversal of 20515400218 is 81200451502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81200451502 = 2 ⋅40600225751.

It can be written as a sum of positive squares in only one way, i.e., 20126245689 + 389154529 = 141867^2 + 19727^2 .

It is a super-2 number, since 2×20515400218² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5128850053 + ... + 5128850056.

Almost surely, 2^20515400218 is an apocalyptic number.

20515400218 is a deficient number, since it is larger than the sum of its proper divisors (10257700112).

20515400218 is a wasteful number, since it uses less digits than its factorization.

20515400218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10257700111.

The product of its (nonzero) digits is 3200, while the sum is 28.

The spelling of 20515400218 in words is "twenty billion, five hundred fifteen million, four hundred thousand, two hundred eighteen".