21211256451 has 32 divisors (see below), whose sum is σ = 35278848000. Its totient is φ = 11013029280.

The previous prime is 21211256401. The next prime is 21211256471. The reversal of 21211256451 is 15465211212.

It is not a de Polignac number, because 21211256451 - 2⁹ = 21211255939 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21211256401) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 433950 + ... + 480348.

It is an arithmetic number, because the mean of its divisors is an integer number (1102464000).

Almost surely, 2^21211256451 is an apocalyptic number.

21211256451 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21211256451 is a deficient number, since it is larger than the sum of its proper divisors (14067591549).

21211256451 is a wasteful number, since it uses less digits than its factorization.

21211256451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48399.

The product of its digits is 4800, while the sum is 30.

Adding to 21211256451 its reverse (15465211212), we get a palindrome (36676467663).

The spelling of 21211256451 in words is "twenty-one billion, two hundred eleven million, two hundred fifty-six thousand, four hundred fifty-one".