21421786 has 16 divisors (see below), whose sum is σ = 33747264. Its totient is φ = 10178784.

The previous prime is 21421769. The next prime is 21421793. The reversal of 21421786 is 68712412.

It is a pancake number, because a pancake can be divided into 21421786 parts by 6545 straight cuts.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6070 + ... + 8926.

It is an arithmetic number, because the mean of its divisors is an integer number (2109204).

Almost surely, 2^21421786 is an apocalyptic number.

21421786 is a deficient number, since it is larger than the sum of its proper divisors (12325478).

21421786 is a wasteful number, since it uses less digits than its factorization.

21421786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3045.

The product of its digits is 5376, while the sum is 31.

The square root of 21421786 is about 4628.3675307823. The cubic root of 21421786 is about 277.7272915298.

The spelling of 21421786 in words is "twenty-one million, four hundred twenty-one thousand, seven hundred eighty-six".