21698763025 has 27 divisors (see below), whose sum is σ = 28598803891. Its totient is φ = 16328464640.

The previous prime is 21698763011. The next prime is 21698763041. The reversal of 21698763025 is 52036789612.

The square root of 21698763025 is 147305.

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

It can be written as a sum of positive squares in 13 ways, for example, as 8744681169 + 12954081856 = 93513^2 + 113816^2 .

It is not a de Polignac number, because 21698763025 - 2¹⁵ = 21698730257 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21698763025.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 12520059 + ... + 12521791.

Almost surely, 2^21698763025 is an apocalyptic number.

21698763025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21698763025 is the 147305-th square number.

21698763025 is the 73653-rd centered octagonal number.

It is an amenable number.

21698763025 is a deficient number, since it is larger than the sum of its proper divisors (6900040866).

21698763025 is an frugal number, since it uses more digits than its factorization.

21698763025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3510 (or 1755 counting only the distinct ones).

The product of its (nonzero) digits is 1088640, while the sum is 49.

Multiplying 21698763025 by its sum of digits (49), we get a square (1063239388225 = 1031135²).

The spelling of 21698763025 in words is "twenty-one billion, six hundred ninety-eight million, seven hundred sixty-three thousand, twenty-five".