21697154 has 12 divisors (see below), whose sum is σ = 32913234. Its totient is φ = 10727424.

The previous prime is 21697153. The next prime is 21697157. The reversal of 21697154 is 45179612.

It can be written as a sum of positive squares in 3 ways, for example, as 19936225 + 1760929 = 4465^2 + 1327^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21697153) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 18242 + ... + 19394.

Almost surely, 2^21697154 is an apocalyptic number.

21697154 is a deficient number, since it is larger than the sum of its proper divisors (11216080).

21697154 is an equidigital number, since it uses as much as digits as its factorization.

21697154 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1349 (or 1252 counting only the distinct ones).

The product of its digits is 15120, while the sum is 35.

The square root of 21697154 is about 4658.0203949747. The cubic root of 21697154 is about 278.9122508526.

The spelling of 21697154 in words is "twenty-one million, six hundred ninety-seven thousand, one hundred fifty-four".