21211550451 has 96 divisors (see below), whose sum is σ = 38360649600. Its totient is φ = 10996992000.

The previous prime is 21211550447. The next prime is 21211550461. The reversal of 21211550451 is 15405511212.

It is a happy number.

It is not a de Polignac number, because 21211550451 - 2² = 21211550447 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21211550411) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 12324271 + ... + 12325991.

It is an arithmetic number, because the mean of its divisors is an integer number (399590100).

Almost surely, 2^21211550451 is an apocalyptic number.

21211550451 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21211550451 is a deficient number, since it is larger than the sum of its proper divisors (17149099149).

21211550451 is a wasteful number, since it uses less digits than its factorization.

21211550451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1997 (or 1994 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 27.

The spelling of 21211550451 in words is "twenty-one billion, two hundred eleven million, five hundred fifty thousand, four hundred fifty-one".