20551511656 has 16 divisors (see below), whose sum is σ = 41498244900. Its totient is φ = 9485313024.

The previous prime is 20551511653. The next prime is 20551511677. The reversal of 20551511656 is 65611515502.

It can be written as a sum of positive squares in 2 ways, for example, as 19525590756 + 1025920900 = 139734^2 + 32030^2 .

It is not an unprimeable number, because it can be changed into a prime (20551511653) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 98805241 + ... + 98805448.

Almost surely, 2^20551511656 is an apocalyptic number.

20551511656 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

20551511656 is an abundant number, since it is smaller than the sum of its proper divisors (20946733244).

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

20551511656 is a wasteful number, since it uses less digits than its factorization.

20551511656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197610708 (or 197610704 counting only the distinct ones).

The product of its (nonzero) digits is 45000, while the sum is 37.

The spelling of 20551511656 in words is "twenty billion, five hundred fifty-one million, five hundred eleven thousand, six hundred fifty-six".