21194992225 has 27 divisors (see below), whose sum is σ = 28899166611. Its totient is φ = 15408716400.

The previous prime is 21194992219. The next prime is 21194992241. The reversal of 21194992225 is 52229949112.

It is a happy number.

The square root of 21194992225 is 145585.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 7630197201 + 13564795024 = 87351^2 + 116468^2 .

It is not a de Polignac number, because 21194992225 - 2¹³ = 21194984033 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 8005852 + ... + 8008498.

Almost surely, 2^21194992225 is an apocalyptic number.

21194992225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21194992225 is the 145585-th square number.

21194992225 is the 72793-rd centered octagonal number.

It is an amenable number.

21194992225 is a deficient number, since it is larger than the sum of its proper divisors (7704174386).

21194992225 is an frugal number, since it uses more digits than its factorization.

21194992225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5326 (or 2663 counting only the distinct ones).

The product of its digits is 233280, while the sum is 46.

It can be divided in two parts, 211 and 94992225, that added together give a triangular number (94992436 = T₁₃₇₈₃).

The spelling of 21194992225 in words is "twenty-one billion, one hundred ninety-four million, nine hundred ninety-two thousand, two hundred twenty-five".