21151351551 has 32 divisors (see below), whose sum is σ = 32397742080. Its totient is φ = 12139480800.

The previous prime is 21151351541. The next prime is 21151351591. The reversal of 21151351551 is 15515315112.

It is not a de Polignac number, because 21151351551 - 2⁷ = 21151351423 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21151351511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2091016 + ... + 2101106.

It is an arithmetic number, because the mean of its divisors is an integer number (1012429440).

Almost surely, 2^21151351551 is an apocalyptic number.

21151351551 is a deficient number, since it is larger than the sum of its proper divisors (11246390529).

21151351551 is a wasteful number, since it uses less digits than its factorization.

21151351551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13467.

The product of its digits is 3750, while the sum is 30.

Adding to 21151351551 its reverse (15515315112), we get a palindrome (36666666663).

The spelling of 21151351551 in words is "twenty-one billion, one hundred fifty-one million, three hundred fifty-one thousand, five hundred fifty-one".