20751891264 has 126 divisors (see below), whose sum is σ = 64409317206. Its totient is φ = 6385167360.

The previous prime is 20751891233. The next prime is 20751891269. The reversal of 20751891264 is 46219815702.

20751891264 is a `hidden beast` number, since 2 + 0 + 7 + 518 + 9 + 126 + 4 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 1654862400 + 19097028864 = 40680^2 + 138192^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20751891269) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 9247 + ... + 203934.

Almost surely, 2^20751891264 is an apocalyptic number.

20751891264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20751891264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32204658603).

20751891264 is an abundant number, since it is smaller than the sum of its proper divisors (43657425942).

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

20751891264 is a wasteful number, since it uses less digits than its factorization.

20751891264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213225 (or 213199 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The spelling of 20751891264 in words is "twenty billion, seven hundred fifty-one million, eight hundred ninety-one thousand, two hundred sixty-four".