21491625501 has 24 divisors (see below), whose sum is σ = 31950041760. Its totient is φ = 13915180896.

The previous prime is 21491625499. The next prime is 21491625503. The reversal of 21491625501 is 10552619412.

21491625501 is a `hidden beast` number, since 2 + 1 + 4 + 91 + 62 + 5 + 501 = 666.

It is an interprime number because it is at equal distance from previous prime (21491625499) and next prime (21491625503).

It is not a de Polignac number, because 21491625501 - 2¹ = 21491625499 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21491625503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 199746 + ... + 287891.

It is an arithmetic number, because the mean of its divisors is an integer number (1331251740).

Almost surely, 2^21491625501 is an apocalyptic number.

It is an amenable number.

21491625501 is a deficient number, since it is larger than the sum of its proper divisors (10458416259).

21491625501 is a wasteful number, since it uses less digits than its factorization.

21491625501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 487785 (or 487782 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The spelling of 21491625501 in words is "twenty-one billion, four hundred ninety-one million, six hundred twenty-five thousand, five hundred one".