21507163851 has 8 divisors (see below), whose sum is σ = 28726618320. Its totient is φ = 14312909312.

The previous prime is 21507163807. The next prime is 21507163919. The reversal of 21507163851 is 15836170512.

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

It is a cyclic number.

It is not a de Polignac number, because 21507163851 - 2⁷ = 21507163723 is a prime.

It is a super-2 number, since 2×21507163851² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21507163751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6297990 + ... + 6301403.

It is an arithmetic number, because the mean of its divisors is an integer number (3590827290).

Almost surely, 2^21507163851 is an apocalyptic number.

21507163851 is a deficient number, since it is larger than the sum of its proper divisors (7219454469).

21507163851 is a wasteful number, since it uses less digits than its factorization.

21507163851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12599965.

The product of its (nonzero) digits is 50400, while the sum is 39.

The spelling of 21507163851 in words is "twenty-one billion, five hundred seven million, one hundred sixty-three thousand, eight hundred fifty-one".