21691498 has 8 divisors (see below), whose sum is σ = 32628960. Its totient is φ = 10815180.

The previous prime is 21691489. The next prime is 21691513. The reversal of 21691498 is 89419612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21691498.

It is an unprimeable number.

It is an upside-down number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14388 + ... + 15823.

It is an arithmetic number, because the mean of its divisors is an integer number (4078620).

Almost surely, 2^21691498 is an apocalyptic number.

21691498 is a deficient number, since it is larger than the sum of its proper divisors (10937462).

21691498 is a wasteful number, since it uses less digits than its factorization.

21691498 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30572.

The product of its digits is 31104, while the sum is 40.

The square root of 21691498 is about 4657.4132305390. The cubic root of 21691498 is about 278.8880131916. Note that the first 3 decimals are identical.

The spelling of 21691498 in words is "twenty-one million, six hundred ninety-one thousand, four hundred ninety-eight".