21506005662025 has 12 divisors (see below), whose sum is σ = 26668198747072. Its totient is φ = 17204319545040.

The previous prime is 21506005662019. The next prime is 21506005662077. The reversal of 21506005662025 is 52026650060512.

It is not a de Polignac number, because 21506005662025 - 2¹⁷ = 21506005530953 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11218677 + ... + 12995026.

Almost surely, 2^{21506005662025} is an apocalyptic number.

21506005662025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21506005662025 is a deficient number, since it is larger than the sum of its proper divisors (5162193085047).

21506005662025 is a wasteful number, since it uses less digits than its factorization.

21506005662025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24249240 (or 24249235 counting only the distinct ones).

The product of its (nonzero) digits is 216000, while the sum is 40.

The spelling of 21506005662025 in words is "twenty-one trillion, five hundred six billion, five million, six hundred sixty-two thousand, twenty-five".