21511010025 has 72 divisors (see below), whose sum is σ = 40009453120. Its totient is φ = 11457080640.

The previous prime is 21511009991. The next prime is 21511010029. The reversal of 21511010025 is 52001011512.

It is not a de Polignac number, because 21511010025 - 2¹⁴ = 21510993641 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21511010029) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 5580999 + ... + 5584851.

Almost surely, 2^21511010025 is an apocalyptic number.

21511010025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21511010025 is a deficient number, since it is larger than the sum of its proper divisors (18498443095).

21511010025 is an equidigital number, since it uses as much as digits as its factorization.

21511010025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4797 (or 4780 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 18.

Adding to 21511010025 its reverse (52001011512), we get a palindrome (73512021537).

The spelling of 21511010025 in words is "twenty-one billion, five hundred eleven million, ten thousand, twenty-five".